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 (
    89591, 89592, 86226, 86237, 86230, 91993, 
    91994, 91995, 91996, 91997, 91998, 
    91999, 82362, 91960, 82360, 91953, 
    91954, 91955, 91956, 91957, 91958, 
    91959, 84290, 82404, 82342, 82367, 
    86236, 86222, 82338, 82337
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00087

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 (89591,89592,86226,86237,86230,91993,91994,91995,91996,91997,91998,91999,82362,91960,82360,91953,91954,91955,91956,91957,91958,91959,84290,82404,82342,82367,86236,86222,82338,82337)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}