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 (
    100552, 100553, 100554, 100555, 100556, 
    100557, 100558, 100561, 100564, 100565, 
    100566, 100567, 100568, 100569, 100570, 
    100571, 100572, 100573, 100574, 100575, 
    100576, 100577, 100578, 100579, 100580, 
    100581, 100586, 100587, 100588, 100591, 
    101576, 101577, 101578, 101581, 101582, 
    101583, 101584, 101585, 101586, 101587, 
    101588, 101591, 101594, 101595, 101596, 
    101597, 101598, 101599
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00100

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "table": {
      "table_name": "cscart_product_descriptions",
      "access_type": "range",
      "possible_keys": [
        "PRIMARY",
        "product_id"
      ],
      "key": "PRIMARY",
      "used_key_parts": [
        "product_id",
        "lang_code"
      ],
      "key_length": "9",
      "rows_examined_per_scan": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (100552,100553,100554,100555,100556,100557,100558,100561,100564,100565,100566,100567,100568,100569,100570,100571,100572,100573,100574,100575,100576,100577,100578,100579,100580,100581,100586,100587,100588,100591,101576,101577,101578,101581,101582,101583,101584,101585,101586,101587,101588,101591,101594,101595,101596,101597,101598,101599)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
100552
100553
100554
100555
100556
100557
100558
100561
100564
100565
100566
100567
100568
100569
100570
100571
100572
100573
100574
100575
100576
100577
100578
100579
100580
100581
100586
100587
100588
100591
101576
101577
101578
101581
101582
101583
101584
101585
101586
101587
101588
101591
101594
101595
101596
101597
101598
101599