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 (
    1896, 33725, 1893, 38074, 49164, 48846, 
    1894, 23152, 49873, 1057, 1103, 1102, 
    1104, 398, 1716, 1277, 43824, 34668, 
    34667, 1105, 1107, 854, 43825, 2238, 
    1106, 397, 34669, 34666, 386, 2620, 
    33724, 856
  ) 
  AND cscart_product_descriptions.lang_code = 'vi'

Query time 0.02043

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 (1896,33725,1893,38074,49164,48846,1894,23152,49873,1057,1103,1102,1104,398,1716,1277,43824,34668,34667,1105,1107,854,43825,2238,1106,397,34669,34666,386,2620,33724,856) and cscart_product_descriptions.lang_code = 'vi'"
        }
      }
    ]
  }
}