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 (
    82561, 90268, 90264, 90266, 90273, 91311, 
    91313, 91315, 90267, 90274, 85649, 
    85650, 85651, 91312, 91314, 91316, 
    90263, 90270, 90269, 90275, 90265, 
    93356, 93357, 93358, 94117, 94958, 
    95683, 95702, 95703, 96841, 96918, 
    96919, 96998, 98538, 98539, 98540, 
    98541, 98542, 98543, 98544, 98545, 
    98546, 98547, 98548, 98549, 100971, 
    100972, 100973
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00096

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "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": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (82561,90268,90264,90266,90273,91311,91313,91315,90267,90274,85649,85650,85651,91312,91314,91316,90263,90270,90269,90275,90265,93356,93357,93358,94117,94958,95683,95702,95703,96841,96918,96919,96998,98538,98539,98540,98541,98542,98543,98544,98545,98546,98547,98548,98549,100971,100972,100973)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
82561 nuie Wetroom Screen Support Arm - Chrome
85649 Hudson Reed Wetroom Screen Support Arm - Polished Chrome
85650 Hudson Reed Wetroom Screen Support Arm - Matt Black
85651 Hudson Reed Wetroom Screen Support Arm - Brushed Brass
90263 nuie Wetroom Screen Support Foot - Polished Chrome
90264 nuie 3000mm Wetroom Screen Ceiling Post - Polished Chrome
90265 Hudson Reed Wetroom Screen Horseshoe Support - Polished Chrome
90266 Hudson Reed Wetroom Wall Channel 1950mm Black - Matt Black
90267 RETURN SCREEN 'L' PROFILE Kit Black - Matt Black
90268 nuie Black Wetroom Screen Ceiling Post - Matt Black
90269 Hudson Reed Wetroom Screen Horseshoe Support Foot - Matt Black
90270 nuie Black Wetroom Foot and Wall Bracket - Matt Black
90273 Hudson Reed Wetroom Wall Channel 1950mm Brass - Brushed Brass
90274 Return Screen L Profile Kit 1950mm Brass - Brushed Brass
90275 Hudson Reed Wetroom Screen Horseshoe Support - Brushed Brass
91311 Hudson Reed Wetroom Screen Accessories Flat Support Bar, 1202mm - Chrome
91312 Hudson Reed Wetroom Screen Accessories Support Arm T Piece, 19mm x 53mm x 53mm - Chrome
91313 Hudson Reed Wetroom Screen Accessories Flat Support Bar, 1202mm - Matt Black
91314 Hudson Reed Wetroom Screen Accessories Support Arm T Piece, 19mm x 53mm x 53mm - Matt Black
91315 Hudson Reed Wetroom Screen Accessories Flat Support Bar, 1202mm - Brushed Brass
91316 Hudson Reed Wetroom Screen Accessories Support Arm T Piece, 19mm x 53mm x 53mm - Brushed Brass
93356
93357
93358
94117
94958
95683
95702
95703
96841
96918
96919
96998
98538
98539
98540
98541
98542
98543
98544
98545
98546
98547
98548
98549
100971
100972
100973