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 (
    3196, 33703, 37282, 40759, 33701, 37885, 
    2151, 6045, 40811, 5642, 2472, 47604, 
    6363, 15613, 2473, 3991, 3465, 5643, 
    4823, 37295, 5772, 2565, 37298, 1850, 
    2155, 47592, 2626, 26862, 41130, 37280, 
    21746, 37881
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.00660

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 (3196,33703,37282,40759,33701,37885,2151,6045,40811,5642,2472,47604,6363,15613,2473,3991,3465,5643,4823,37295,5772,2565,37298,1850,2155,47592,2626,26862,41130,37280,21746,37881) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}