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 (
    3884, 382, 3875, 2294, 112, 3471, 3880, 
    3877, 49265, 3859, 3879, 3881, 23162, 
    3860, 6089, 1781, 384, 3883, 385, 3882, 
    1755, 383, 4020, 1754, 4493, 41398, 
    52, 41399, 5581, 5577, 4500, 1059
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.01675

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 (3884,382,3875,2294,112,3471,3880,3877,49265,3859,3879,3881,23162,3860,6089,1781,384,3883,385,3882,1755,383,4020,1754,4493,41398,52,41399,5581,5577,4500,1059) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}