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 (
    85654, 84105, 83099, 92839, 92897, 92898, 
    92900, 92903, 92904, 92907, 92908, 
    92911, 92912, 92935, 92937, 92939, 
    92941, 92943, 92945, 93054, 93055, 
    93056, 93057, 93058, 93059, 93060, 
    93061, 93070, 93281, 93524, 93526, 
    93528, 93782, 93784, 93786, 94027, 
    94029, 94031, 94033, 94075, 94717, 
    94720, 94721, 94724, 94725, 94726, 
    94729, 94730, 94733, 94734, 94737, 
    94738, 94741, 94742, 94745, 94746, 
    94749, 96304, 96308, 96310, 96311, 
    96313, 96314, 96316, 96318, 96319, 
    96321, 96323, 96325, 96327, 96329, 
    96331, 96333, 96337, 97015, 97017, 
    97024, 97027, 97028, 97029, 97031, 
    97033, 97040, 97046, 97841, 97844, 
    97845, 97848, 97849, 97850, 97853, 
    97854, 97857, 97858, 97861, 97862
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00157

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "43.24"
    },
    "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": 96,
      "rows_produced_per_join": 96,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "33.64",
        "eval_cost": "9.60",
        "prefix_cost": "43.24",
        "data_read_per_join": "366K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (85654,84105,83099,92839,92897,92898,92900,92903,92904,92907,92908,92911,92912,92935,92937,92939,92941,92943,92945,93054,93055,93056,93057,93058,93059,93060,93061,93070,93281,93524,93526,93528,93782,93784,93786,94027,94029,94031,94033,94075,94717,94720,94721,94724,94725,94726,94729,94730,94733,94734,94737,94738,94741,94742,94745,94746,94749,96304,96308,96310,96311,96313,96314,96316,96318,96319,96321,96323,96325,96327,96329,96331,96333,96337,97015,97017,97024,97027,97028,97029,97031,97033,97040,97046,97841,97844,97845,97848,97849,97850,97853,97854,97857,97858,97861,97862)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
83099 nuie Arvan Wall Mounted Bath Shower Mixer With Kit - Chrome
84105 nuie Binsey Wall Mounted Bath Shower Mixer With Kit - Chrome
85654 nuie Series Two Bath Shower Mixer - Chrome
92839
92897
92898
92900
92903
92904
92907
92908
92911
92912
92935
92937
92939
92941
92943
92945
93054
93055
93056
93057
93058
93059
93060
93061
93070
93281
93524
93526
93528
93782
93784
93786
94027
94029
94031
94033
94075
94717
94720
94721
94724
94725
94726
94729
94730
94733
94734
94737
94738
94741
94742
94745
94746
94749
96304
96308
96310
96311
96313
96314
96316
96318
96319
96321
96323
96325
96327
96329
96331
96333
96337
97015
97017
97024
97027
97028
97029
97031
97033
97040
97046
97841
97844
97845
97848
97849
97850
97853
97854
97857
97858
97861
97862