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 (
    85297, 85392, 85394, 85443, 85445, 85494, 
    85496, 85341, 85343, 89755, 89757, 
    91131, 91132, 91135, 91136, 91138, 
    91139, 91140, 91217, 91218, 91221, 
    91222, 91224, 91225, 91226, 91272, 
    91273, 91276, 91277, 91279
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00085

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (85297,85392,85394,85443,85445,85494,85496,85341,85343,89755,89757,91131,91132,91135,91136,91138,91139,91140,91217,91218,91221,91222,91224,91225,91226,91272,91273,91276,91277,91279)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}