SELECT 
  cscart_product_descriptions.product_id, 
  cscart_product_descriptions.short_description, 
  IF(
    cscart_product_descriptions.short_description = '' 
    OR cscart_product_descriptions.short_description IS NULL, 
    cscart_product_descriptions.full_description, 
    ''
  ) AS full_description 
FROM 
  cscart_product_descriptions 
WHERE 
  cscart_product_descriptions.product_id IN (
    222908, 232082, 234216, 232003, 219459, 
    220542, 230954, 225197, 234939, 222816, 
    218954, 221515, 225536, 222805, 224978
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00147

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": ["PRIMARY", "product_id"],
      "key": "product_id",
      "key_length": "9",
      "used_key_parts": ["product_id", "lang_code"],
      "rows": 15,
      "filtered": 100,
      "index_condition": "cscart_product_descriptions.product_id in (222908,232082,234216,232003,219459,220542,230954,225197,234939,222816,218954,221515,225536,222805,224978) and cscart_product_descriptions.lang_code = 'en'"
    }
  }
}