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 (
    222, 18160, 2457, 2257, 2019, 1835, 4070, 
    48772, 38552, 20804, 2150, 4263, 4880, 
    46749, 3777, 729, 3754, 39612, 37494, 
    18748, 5624, 2437, 4047, 5629, 33697, 
    2258, 1408, 47148, 992, 4502, 4262, 
    6603
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.03129

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": 32,
          "filtered": 100,
          "index_condition": "cscart_product_descriptions.product_id in (222,18160,2457,2257,2019,1835,4070,48772,38552,20804,2150,4263,4880,46749,3777,729,3754,39612,37494,18748,5624,2437,4047,5629,33697,2258,1408,47148,992,4502,4262,6603) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}