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 (
    89721, 86874, 86872, 86875, 86883, 86870, 
    86868, 86871, 86873, 86869, 86881, 
    86878, 86879, 89720, 86876, 86886, 
    89719, 89722, 86877, 86882, 86884, 
    86885, 89579, 89581, 89583, 89585, 
    89587, 89578, 89580, 89582, 89584, 
    89586, 89588, 89577, 85567, 89576, 
    94024, 94025, 94429, 94430, 94431, 
    94432, 94433, 94434, 94441, 95100, 
    95558, 95559, 95560, 95638, 95640, 
    95645, 95646, 95653, 95790, 95933, 
    95936, 95940, 96522, 96523, 96524, 
    96525, 96526, 96527, 96528, 96677, 
    96679, 96684, 96685, 96693, 98445, 
    98682, 99507, 99511, 99515, 100361, 
    100362, 100363, 100364, 100365, 100366, 
    100367, 100368, 100369, 100370, 100371, 
    100372, 100373, 100384, 100385, 101047, 
    101048, 101049, 101050, 101051, 101052
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00178

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 (89721,86874,86872,86875,86883,86870,86868,86871,86873,86869,86881,86878,86879,89720,86876,86886,89719,89722,86877,86882,86884,86885,89579,89581,89583,89585,89587,89578,89580,89582,89584,89586,89588,89577,85567,89576,94024,94025,94429,94430,94431,94432,94433,94434,94441,95100,95558,95559,95560,95638,95640,95645,95646,95653,95790,95933,95936,95940,96522,96523,96524,96525,96526,96527,96528,96677,96679,96684,96685,96693,98445,98682,99507,99511,99515,100361,100362,100363,100364,100365,100366,100367,100368,100369,100370,100371,100372,100373,100384,100385,101047,101048,101049,101050,101051,101052)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
85567 nuie Wastes & Extras Easyclean Shower Tray Waste - Chrome
86868 nuie Leg Set Suitable for 700-900mm Square & Rectangular Trays - Slate Grey
86869 nuie Leg Set Suitable for 700-900mm Square & Rectangular Trays - White
86870 nuie Leg Set Suitable for 1000mm Square & Rectangular Trays - Slate Grey
86871 nuie Leg Set Suitable for 1000mm Square & Rectangular Trays - White
86872 nuie Leg Set Suitable for 1100-1200mm Rectangular Trays - Slate Grey
86873 nuie Leg Set Suitable for 1100-1200mm Rectangular Trays - White
86874 nuie Leg Set Suitable for 1300-1800mm Rectangular & Walk in Trays - Slate Grey
86875 nuie Leg Set Suitable for 1300-1800mm Rectangular & Walk in Trays - White
86876 nuie Leg Set Suitable for 700-900mm Quadrant & Offset Quadrant Trays - Slate Grey
86877 nuie Leg Set Suitable for 700-900mm Quadrant & Offset Quadrant Trays - White
86878 nuie Leg Set Suitable for 1000-1200mm Quadrant & Offset Quadrant Trays - Slate Grey
86879 nuie Leg Set Suitable for 1000-1200mm Quadrant & Offset Quadrant Trays - White
86881 nuie Leg Set & Plinth Kit (1000mm Plinth x 2) - White
86882 nuie Leg Set & Plinth Kit (900 x 900mm Curved Plinth) - White
86883 nuie Leg Set & Plinth Kit (1700 & 1000mm Plinth) - White
86884 nuie Leg Set & Plinth Kit (1200 x 900mm Curved Plinth) - White
86885 nuie Leg Set & Plinth Kit (1000 x 1000mm Curved Plinth) - White
86886 nuie Leg Set & Plinth Kit For D-Shaped Tray - White
89576 nuie 90mm Fast Flow Shower Waste - White/Chrome
89577 nuie Square Shower Waste Chrome Top - Chrome/White
89578 nuie 90mm Fast Flow Shower Waste - Black/Black
89579 nuie Square Shower Waste Black Top - Black
89580 nuie 90mm Fast Flow Shower Waste - White/White
89581 nuie Square Shower Waste White Top - White
89582 nuie 90mm Fast Flow Shower Waste - White/Brushed Brass
89583 nuie Square Shower Waste Brushed Brass Top - Brushed Brass/White
89584 nuie 90mm Fast Flow Shower Waste - Black/Brushed Brass
89585 nuie Square Shower Waste Brushed Brass Top - Brushed Brass/Black
89586 nuie 90mm Fast Flow Shower Waste - Black/Chrome
89587 nuie Square Shower Waste Chrome Top - Chrome/Black
89588 nuie Mega Flow Shower Waste Gun Metal Top - Gun Metal
89719 nuie Leg Set & Plinth Kit (1000 x 1000 Panel) - Slate Grey
89720 nuie Leg Set & Plinth Kit (900 x 900 Panel) - Slate Grey
89721 nuie Leg Set & Plinth Kit (1700 & 1000 Panel) - Slate Grey
89722 nuie Leg Set & Plinth Kit (1200 x 900 Panel) - Slate Grey
94024
94025
94429
94430
94431
94432
94433
94434
94441
95100
95558
95559
95560
95638
95640
95645
95646
95653
95790
95933
95936
95940
96522
96523
96524
96525
96526
96527
96528
96677
96679
96684
96685
96693
98445
98682
99507
99511
99515
100361
100362
100363
100364
100365
100366
100367
100368
100369
100370
100371
100372
100373
100384
100385
101047
101048
101049
101050
101051
101052