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 (
    389383, 389406, 389520, 389423, 389225, 
    389199, 389424, 435241, 389256, 429392, 
    381743, 435252, 388364, 389301, 390097, 
    429396, 388365, 389479, 389345, 389257
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00100

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "28.04"
    },
    "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": 20,
      "rows_produced_per_join": 20,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "24.04",
        "eval_cost": "4.00",
        "prefix_cost": "28.04",
        "data_read_per_join": "136K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`webmarco`.`cscart_product_descriptions`.`product_id` in (389383,389406,389520,389423,389225,389199,389424,435241,389256,429392,381743,435252,388364,389301,390097,429396,388365,389479,389345,389257)) and (`webmarco`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}