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 (
    5983, 40760, 3491, 1532, 2693, 6141, 
    28151, 28388, 5714, 26847, 6136, 47904, 
    6131, 6147, 6159, 6537, 38743, 41599, 
    5980, 41605, 46143, 3492, 31608, 6140, 
    26919, 40759, 26865, 26965, 6617, 4140, 
    5809, 41604
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.02056

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 (5983,40760,3491,1532,2693,6141,28151,28388,5714,26847,6136,47904,6131,6147,6159,6537,38743,41599,5980,41605,46143,3492,31608,6140,26919,40759,26865,26965,6617,4140,5809,41604) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}