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 (
    2716, 5649, 930, 26909, 6601, 23034, 
    708, 5823, 5642, 4448, 1676, 2441, 57, 
    2793, 1668, 1930, 22302, 928, 3497, 
    21192, 4451, 6197, 4105, 4453, 1994, 
    3696, 37945, 5643, 29776, 2436, 37939, 
    1700
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.02153

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 (2716,5649,930,26909,6601,23034,708,5823,5642,4448,1676,2441,57,2793,1668,1930,22302,928,3497,21192,4451,6197,4105,4453,1994,3696,37945,5643,29776,2436,37939,1700) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}