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 (
    91042, 90008, 90564, 90570, 90576, 84678, 
    87304, 87305, 87316, 87317, 87328, 
    87329, 87340, 87341, 89818, 89819, 
    89870, 89871, 89942, 89943, 91508, 
    91509, 83083, 83084
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00083

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "10.82"
    },
    "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": 24,
      "rows_produced_per_join": 24,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "8.42",
        "eval_cost": "2.40",
        "prefix_cost": "10.82",
        "data_read_per_join": "91K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (91042,90008,90564,90570,90576,84678,87304,87305,87316,87317,87328,87329,87340,87341,89818,89819,89870,89871,89942,89943,91508,91509,83083,83084)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}