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 (
    99235, 99236, 99237, 99238, 99240, 99242, 
    99243, 99244, 99245, 99246, 99247, 
    99249, 99250, 99251, 99252, 99253, 
    99254, 99255, 99256, 99258, 99259, 
    99260, 99261, 99263, 99264, 99265, 
    99266, 99268, 99269, 99270
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00112

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 (99235,99236,99237,99238,99240,99242,99243,99244,99245,99246,99247,99249,99250,99251,99252,99253,99254,99255,99256,99258,99259,99260,99261,99263,99264,99265,99266,99268,99269,99270)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}