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 (
    89656, 89698, 89655, 86874, 88375, 88376, 
    88331, 88332, 88339, 88370, 88371, 
    89697, 88328, 88327, 88329, 88326, 
    86872, 88368, 88369, 88373, 86875, 
    88325, 86883, 86870, 88372, 88324, 
    88367, 88323, 86868, 86871, 86873, 
    88366, 86869, 86881, 86878, 86879, 
    89720, 86876, 86886, 89719, 89722, 
    86877, 86882, 86884, 86885, 89579, 
    89581, 89583
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00098

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 (89656,89698,89655,86874,88375,88376,88331,88332,88339,88370,88371,89697,88328,88327,88329,88326,86872,88368,88369,88373,86875,88325,86883,86870,88372,88324,88367,88323,86868,86871,86873,88366,86869,86881,86878,86879,89720,86876,86886,89719,89722,86877,86882,86884,86885,89579,89581,89583)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}