SELECT 
  products.company_id as variant_id, 
  companies.company as variant 
FROM 
  cscart_products as products 
  LEFT JOIN cscart_companies AS companies ON companies.company_id = products.company_id 
  INNER JOIN cscart_products_categories as products_categories ON products_categories.product_id = products.product_id 
  INNER JOIN cscart_categories ON cscart_categories.category_id = products_categories.category_id 
  AND (
    cscart_categories.usergroup_ids = '' 
    OR FIND_IN_SET(
      0, cscart_categories.usergroup_ids
    ) 
    OR FIND_IN_SET(
      1, cscart_categories.usergroup_ids
    )
  ) 
  AND cscart_categories.status IN ('A', 'H') 
  AND cscart_categories.storefront_id IN (0, 1) 
  LEFT JOIN cscart_warehouses_sum_products_amount as war_sum_amount ON war_sum_amount.product_id = products.product_id 
  LEFT JOIN cscart_warehouses_destination_products_amount AS warehouses_destination_products_amount ON warehouses_destination_products_amount.product_id = products.product_id 
  AND warehouses_destination_products_amount.destination_id = 0 
  AND warehouses_destination_products_amount.storefront_id = 0 
  LEFT JOIN cscart_product_popularity as popularity ON popularity.product_id = products.product_id 
WHERE 
  1 = 1 
  AND cscart_categories.category_id IN (
    18, 165, 166, 167, 572, 573, 168, 169, 
    170, 171, 172, 173, 174, 175, 176, 177, 
    178, 179, 180
  ) 
  AND (
    (
      CASE products.is_stock_split_by_warehouses WHEN 'Y' THEN warehouses_destination_products_amount.amount ELSE products.amount END
    ) > 0 
    OR products.tracking = 'D' 
    OR products.tracking IS NULL
  ) 
  AND (
    products.usergroup_ids = '' 
    OR FIND_IN_SET(0, products.usergroup_ids) 
    OR FIND_IN_SET(1, products.usergroup_ids)
  ) 
  AND products.status IN ('A') 
  AND products.parent_product_id = 0 
  AND products.status = 'A' 
  AND products.amount != 0 
GROUP BY 
  products.company_id 
ORDER BY 
  companies.company ASC

Query time 0.05177

JSON explain

{
  "query_block": {
    "select_id": 1,
    "filesort": {
      "sort_key": "companies.company",
      "temporary_table": {
        "table": {
          "table_name": "cscart_categories",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "c_status", "p_category_id"],
          "key": "p_category_id",
          "key_length": "3",
          "used_key_parts": ["category_id"],
          "rows": 19,
          "filtered": 100,
          "index_condition": "cscart_categories.category_id in (18,165,166,167,572,573,168,169,170,171,172,173,174,175,176,177,178,179,180) and (cscart_categories.usergroup_ids = '' or find_in_set(0,cscart_categories.usergroup_ids) or find_in_set(1,cscart_categories.usergroup_ids)) and cscart_categories.`status` in ('A','H')",
          "attached_condition": "cscart_categories.storefront_id in (0,1)"
        },
        "table": {
          "table_name": "products_categories",
          "access_type": "ref",
          "possible_keys": ["PRIMARY", "pt"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["category_id"],
          "ref": ["staging2_wesave_com.cscart_categories.category_id"],
          "rows": 1188,
          "filtered": 100,
          "using_index": true
        },
        "table": {
          "table_name": "products",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "status", "idx_parent_product_id"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "ref": ["staging2_wesave_com.products_categories.product_id"],
          "rows": 1,
          "filtered": 7.605616093,
          "attached_condition": "products.parent_product_id = 0 and (products.usergroup_ids = '' or find_in_set(0,products.usergroup_ids) or find_in_set(1,products.usergroup_ids)) and products.`status` = 'A' and products.amount <> 0"
        },
        "table": {
          "table_name": "war_sum_amount",
          "access_type": "ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "3",
          "used_key_parts": ["product_id"],
          "ref": ["staging2_wesave_com.products_categories.product_id"],
          "rows": 1,
          "filtered": 100,
          "using_index": true
        },
        "table": {
          "table_name": "warehouses_destination_products_amount",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY", "idx_storefront_id"],
          "key": "PRIMARY",
          "key_length": "9",
          "used_key_parts": ["product_id", "destination_id", "storefront_id"],
          "ref": [
            "staging2_wesave_com.products_categories.product_id",
            "const",
            "const"
          ],
          "rows": 1,
          "filtered": 100,
          "attached_condition": "trigcond(case products.is_stock_split_by_warehouses when 'Y' then warehouses_destination_products_amount.amount else products.amount end > 0 or products.tracking = 'D' or products.tracking is null)"
        },
        "table": {
          "table_name": "companies",
          "access_type": "eq_ref",
          "possible_keys": ["PRIMARY"],
          "key": "PRIMARY",
          "key_length": "4",
          "used_key_parts": ["company_id"],
          "ref": ["staging2_wesave_com.products.company_id"],
          "rows": 1,
          "filtered": 100
        }
      }
    }
  }
}