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 (
    1533, 5544, 5543, 6181, 6180, 2183, 2182, 
    6533, 26927, 5973, 6124, 6534, 6535, 
    26924, 6183, 26920, 6536, 6128, 2181, 
    29737, 41774, 6159, 46143, 26919, 6172, 
    41667, 6125, 26925, 46141, 6169, 26928, 
    3495
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.00897

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 (1533,5544,5543,6181,6180,2183,2182,6533,26927,5973,6124,6534,6535,26924,6183,26920,6536,6128,2181,29737,41774,6159,46143,26919,6172,41667,6125,26925,46141,6169,26928,3495) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}