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 (
    89301, 89299, 89349, 89350, 89263, 89340, 
    82450, 82451, 89339, 89353, 89354, 
    82449, 89355, 89356, 89284, 89293, 
    91944, 89291, 89262, 89285, 82353, 
    89292, 82352, 89287, 89357, 89358, 
    82386, 89402, 89404, 89403
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00086

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 (89301,89299,89349,89350,89263,89340,82450,82451,89339,89353,89354,82449,89355,89356,89284,89293,91944,89291,89262,89285,82353,89292,82352,89287,89357,89358,82386,89402,89404,89403)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}