SELECT 
  company_id 
FROM 
  cscart_wk_vendor_subdomain 
WHERE 
  subdomain = 'staging2' 
  AND status = 'A'

Query time 0.00135

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_wk_vendor_subdomain",
      "access_type": "ALL",
      "rows": 1,
      "filtered": 100,
      "attached_condition": "cscart_wk_vendor_subdomain.subdomain = 'staging2' and cscart_wk_vendor_subdomain.`status` = 'A'"
    }
  }
}