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 (
    4280, 48179, 5230, 5205, 5207, 5226, 
    5250, 4274, 5220, 5218, 5222, 5248, 
    5242, 5246, 5228, 4279, 5238, 5234, 
    5209, 5232, 4273, 5244, 4275, 4276, 
    5213, 5224, 4277, 5240, 5236, 4278
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.00914

JSON explain

{
  "query_block": {
    "select_id": 1,
    "nested_loop": [
      {
        "table": {
          "table_name": "cscart_product_descriptions",
          "access_type": "range",
          "possible_keys": ["PRIMARY", "product_id"],
          "key": "PRIMARY",
          "key_length": "11",
          "used_key_parts": ["product_id", "lang_code"],
          "rows": 30,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (4280,48179,5230,5205,5207,5226,5250,4274,5220,5218,5222,5248,5242,5246,5228,4279,5238,5234,5209,5232,4273,5244,4275,4276,5213,5224,4277,5240,5236,4278) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}