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 (
    18264, 47974, 46982, 464, 3021, 1106, 
    37315, 45446, 44423, 1585, 397, 40447, 
    47163, 1323, 3579, 47162, 34669, 6355, 
    35168, 27262, 47824, 34666, 35166, 
    44945, 35169, 40444, 2303, 41292, 387, 
    31627, 40436, 31910
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.02754

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 (18264,47974,46982,464,3021,1106,37315,45446,44423,1585,397,40447,47163,1323,3579,47162,34669,6355,35168,27262,47824,34666,35166,44945,35169,40444,2303,41292,387,31627,40436,31910) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}