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 (
    431086, 431212, 431369, 431402, 430785, 
    430833, 430987, 431300, 430724, 430941, 
    431081, 431377, 431384, 430733, 431181, 
    431229, 431472, 430956, 431253, 431454, 
    430721, 431387, 431225, 431431, 430682, 
    430951, 431438, 431450, 430716, 431382, 
    431446, 431468, 431401, 431412, 431430, 
    430945, 431143, 431215, 431058, 431170, 
    431294, 431312, 431367, 431460, 430731, 
    431036, 431224, 431259, 431276, 431310, 
    430777, 431332, 431396, 431296, 431298, 
    431414, 431014, 431172, 431207, 431471, 
    431479, 431180, 431233, 431442, 431189, 
    431413, 431455, 431213, 431278, 431351, 
    430970, 430996, 431095, 431299, 431483, 
    431496, 431059, 431075, 431391, 431478, 
    431282, 431436, 431265, 431435, 431489, 
    431232, 431477, 430728, 431449, 431214, 
    431448, 430986, 431379, 431331, 431375, 
    431221, 431323, 431492, 431388, 431475
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00382

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "140.18"
    },
    "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": 100,
      "rows_produced_per_join": 100,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "120.18",
        "eval_cost": "20.00",
        "prefix_cost": "140.18",
        "data_read_per_join": "682K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`webmarco`.`cscart_product_descriptions`.`product_id` in (431086,431212,431369,431402,430785,430833,430987,431300,430724,430941,431081,431377,431384,430733,431181,431229,431472,430956,431253,431454,430721,431387,431225,431431,430682,430951,431438,431450,430716,431382,431446,431468,431401,431412,431430,430945,431143,431215,431058,431170,431294,431312,431367,431460,430731,431036,431224,431259,431276,431310,430777,431332,431396,431296,431298,431414,431014,431172,431207,431471,431479,431180,431233,431442,431189,431413,431455,431213,431278,431351,430970,430996,431095,431299,431483,431496,431059,431075,431391,431478,431282,431436,431265,431435,431489,431232,431477,430728,431449,431214,431448,430986,431379,431331,431375,431221,431323,431492,431388,431475)) and (`webmarco`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
430682
430716
430721
430724
430728
430731
430733
430777
430785
430833
430941
430945
430951
430956
430970
430986
430987
430996
431014
431036
431058
431059
431075
431081
431086
431095
431143
431170
431172
431180
431181
431189
431207
431212
431213
431214
431215
431221
431224
431225
431229
431232
431233
431253
431259
431265
431276
431278
431282
431294
431296
431298
431299
431300
431310
431312
431323
431331
431332
431351
431367
431369
431375
431377
431379
431382
431384
431387
431388
431391
431396
431401
431402
431412
431413
431414
431430
431431
431435
431436
431438
431442
431446
431448
431449
431450
431454
431455
431460
431468
431471
431472
431475
431477
431478
431479
431483
431489
431492
431496