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 (
    90120, 89157, 89548, 90092, 90102, 90111, 
    82329, 86813, 86847, 89100, 89199, 
    82397, 86850, 83114, 83124, 83133, 
    89728, 89733, 90119, 83085, 89121, 
    89162, 89553, 83142, 89158, 89549, 
    89125, 91282, 89198, 84121, 86812, 
    89099, 82334, 82339, 82349, 84913, 
    84916, 84919, 84928, 84931, 86390, 
    89436, 82331, 86845, 91285, 83086, 
    83141, 89122
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00092

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "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": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (90120,89157,89548,90092,90102,90111,82329,86813,86847,89100,89199,82397,86850,83114,83124,83133,89728,89733,90119,83085,89121,89162,89553,83142,89158,89549,89125,91282,89198,84121,86812,89099,82334,82339,82349,84913,84916,84919,84928,84931,86390,89436,82331,86845,91285,83086,83141,89122)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}