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 (
    97851, 97855, 97859, 97863, 97867, 97871, 
    97911, 97912, 97913, 97914, 97943, 
    97944, 97945, 97946, 97968, 98107, 
    98108, 98109, 98110, 98111, 98112, 
    98113, 98114, 98351, 98352, 98353, 
    98354, 98355, 98356, 98357, 98358, 
    98359, 98360, 98361, 98362, 98363, 
    98364, 98365, 98366, 98685, 100145, 
    100891
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00100

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "18.92"
    },
    "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": 42,
      "rows_produced_per_join": 42,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "14.72",
        "eval_cost": "4.20",
        "prefix_cost": "18.92",
        "data_read_per_join": "160K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (97851,97855,97859,97863,97867,97871,97911,97912,97913,97914,97943,97944,97945,97946,97968,98107,98108,98109,98110,98111,98112,98113,98114,98351,98352,98353,98354,98355,98356,98357,98358,98359,98360,98361,98362,98363,98364,98365,98366,98685,100145,100891)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
97851
97855
97859
97863
97867
97871
97911
97912
97913
97914
97943
97944
97945
97946
97968
98107
98108
98109
98110
98111
98112
98113
98114
98351
98352
98353
98354
98355
98356
98357
98358
98359
98360
98361
98362
98363
98364
98365
98366
98685
100145
100891