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 (
    1264, 31960, 4684, 6119, 15030, 38153, 
    47895, 1776, 6121, 5146, 28441, 1062, 
    5457, 5777, 5472, 5578, 47082, 6116, 
    33464, 33374, 28442, 5156, 5588, 6133, 
    19274, 19565, 5462, 37486, 3641, 5776, 
    2155, 3639
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.01466

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 (1264,31960,4684,6119,15030,38153,47895,1776,6121,5146,28441,1062,5457,5777,5472,5578,47082,6116,33464,33374,28442,5156,5588,6133,19274,19565,5462,37486,3641,5776,2155,3639) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}