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 (
    95408, 95409, 95410, 95411, 95412, 95413, 
    95414, 95415, 95416, 95417, 95418, 
    95419, 95420, 95421, 95422, 95423, 
    95442, 95448, 95556, 95557, 95565, 
    95566, 95567, 95568, 95569, 95570, 
    95571, 95572, 95573, 95574
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00064

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "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": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (95408,95409,95410,95411,95412,95413,95414,95415,95416,95417,95418,95419,95420,95421,95422,95423,95442,95448,95556,95557,95565,95566,95567,95568,95569,95570,95571,95572,95573,95574)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
95408
95409
95410
95411
95412
95413
95414
95415
95416
95417
95418
95419
95420
95421
95422
95423
95442
95448
95556
95557
95565
95566
95567
95568
95569
95570
95571
95572
95573
95574