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 (
    26136, 5728, 286, 289, 5730, 5734, 5723, 
    279, 287, 5729, 284, 5733, 290, 5722, 
    5726, 285, 291, 5732, 281, 5721, 5724, 
    280, 5727, 288, 5725, 5731
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.00345

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": 26,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (26136,5728,286,289,5730,5734,5723,279,287,5729,284,5733,290,5722,5726,285,291,5732,281,5721,5724,280,5727,288,5725,5731) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}