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 (
    90140, 90155, 82444, 84068, 84076, 87360, 
    82537, 84094, 90139, 90154, 87355, 
    87419, 82523, 90296, 90303, 82538, 
    83944, 84088, 82525, 90203, 90214, 
    87417, 84093, 85972, 90153, 90168, 
    82438, 87418, 90757, 90285, 90293, 
    82522, 90295, 90302, 84056, 84064, 
    82547, 82443, 91482, 82437, 87416, 
    90152, 90167, 85971, 84067, 84075, 
    82532, 84092
  ) 
  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 (90140,90155,82444,84068,84076,87360,82537,84094,90139,90154,87355,87419,82523,90296,90303,82538,83944,84088,82525,90203,90214,87417,84093,85972,90153,90168,82438,87418,90757,90285,90293,82522,90295,90302,84056,84064,82547,82443,91482,82437,87416,90152,90167,85971,84067,84075,82532,84092)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}