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 (
    430938, 431208, 431241, 431335, 431447, 
    430727, 430973, 430985, 431292, 430752, 
    430757, 430942, 431383, 431488, 431502, 
    430978, 431017, 431210, 431236, 431330, 
    430719, 430929, 431227, 431235, 431427, 
    431466, 430630, 430632, 431263, 431482, 
    430943, 431040, 430955, 431415, 431018, 
    431069, 431364, 430693, 430971, 431361, 
    431378, 381708, 431281, 431421, 431302, 
    431385, 431285, 431369, 430717, 430785, 
    431212, 431402, 430725, 430833, 430941, 
    431086, 430736, 430987, 431384, 430724, 
    430733, 431229, 431300, 431377, 431472, 
    430721, 431223, 431253, 431181, 431454, 
    430682, 430951, 430956, 431081, 431431, 
    431225, 431468, 381715, 431387, 431446, 
    430716, 431401, 431438, 431143, 431382, 
    431412, 431430, 431058, 431170, 430945, 
    431215, 431460, 431224, 431294, 431310, 
    431312, 431367, 431450, 339768, 430731
  ) 
  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 (430938,431208,431241,431335,431447,430727,430973,430985,431292,430752,430757,430942,431383,431488,431502,430978,431017,431210,431236,431330,430719,430929,431227,431235,431427,431466,430630,430632,431263,431482,430943,431040,430955,431415,431018,431069,431364,430693,430971,431361,431378,381708,431281,431421,431302,431385,431285,431369,430717,430785,431212,431402,430725,430833,430941,431086,430736,430987,431384,430724,430733,431229,431300,431377,431472,430721,431223,431253,431181,431454,430682,430951,430956,431081,431431,431225,431468,381715,431387,431446,430716,431401,431438,431143,431382,431412,431430,431058,431170,430945,431215,431460,431224,431294,431310,431312,431367,431450,339768,430731)) and (`webmarco`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
339768 <ul class="show-more-height"><li> \n </li><li class="important"><span class="i1"><span>Αριθμός δοντιών 1:</span></span><span class="i2"><span>137</span></span> \n </li><li><span class="i1"><span>Πλάτος 1 [mm]:</span></span><span class="i2"><span>25,00</span></span> \n </li><li><span class="i1"><span>Προσέξτε τις πληροφορίες σέρβις</span></span> \n </li><li><span class="i1"><span>ΣΕ ΕΝΑ:</span></span><span class="i2"><span>Κιτ ιμάντα χρονισμού</span></span> \n </li><li><span class="i1"><span>Αριθμός αντικειμένου:</span></span><span class="i2"><span>530 0375 10</span></span> \n </li><li><span class="i1"><span>Η τιμή μας:</span></span><span class="i2"><span>50,49 £</span></span> \n </li><li><span class="i1"><span>Αριθμός ανταλλακτικού κατασκευαστή:</span></span><span class="i2"><span>530 0375 10</span></span> \n</li></ul>
381708 <p></p> <p><b>Breakfast Included</b></p> <ul><li>Free WiFi</li><li>Central Heating</li></ul> <p>Our agritourism offers a wide range of tourist services, starting from horseback riding, fishing, bar and restaurant, as well as traditional production of products. Our agritourism is the tranquility that every customer seeks.</p>
381715 <p></p> <p><b>Breakfast Included</b></p><p>€10 for the fireplace</p> <ul><li>Free WiFi</li><li>Central Heating</li></ul> <p>(Portable beds can be added)</p> <p>Our agritourism offers a wide range of tourist services, starting from horseback riding, fishing, bar and restaurant, as well as traditional production of products. Our agritourism is the tranquility that every customer seeks.</p>
430630
430632
430682
430693
430716
430717
430719
430721
430724
430725
430727
430731
430733
430736
430752
430757
430785
430833
430929
430938
430941
430942
430943
430945
430951
430955
430956
430971
430973
430978
430985
430987
431017
431018
431040
431058
431069
431081
431086
431143
431170
431181
431208
431210
431212
431215
431223
431224
431225
431227
431229
431235
431236
431241
431253
431263
431281
431285
431292
431294
431300
431302
431310
431312
431330
431335
431361
431364
431367
431369
431377
431378
431382
431383
431384
431385
431387
431401
431402
431412
431415
431421
431427
431430
431431
431438
431446
431447
431450
431454
431460
431466
431468
431472
431482
431488
431502