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 (
    37943, 931, 329, 31903, 1265, 47164, 
    5274, 38151, 40507, 37283, 31940, 26860, 
    26852, 35178, 5268, 40893, 37954, 32110, 
    38102, 31644, 932, 5645, 5259, 25896, 
    935, 35181, 35183, 1275, 26866, 5284, 
    3598, 37848
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.01098

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 (37943,931,329,31903,1265,47164,5274,38151,40507,37283,31940,26860,26852,35178,5268,40893,37954,32110,38102,31644,932,5645,5259,25896,935,35181,35183,1275,26866,5284,3598,37848) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}