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 (
    91052, 87652, 87658, 87666, 87672, 87673, 
    87679, 87680, 87686, 87701, 87707, 
    87709, 87721, 87723, 87735, 88694, 
    88695, 88741, 88742, 84697, 84698, 
    88946, 88947, 88948, 82404, 88140, 
    88143, 88508, 87252, 87253, 87254, 
    87255, 87256, 87257, 87258, 87259, 
    88102, 88103, 92203, 92449, 82551, 
    82342, 87890, 82367, 88943, 88944, 
    88945, 92168
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00120

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 (91052,87652,87658,87666,87672,87673,87679,87680,87686,87701,87707,87709,87721,87723,87735,88694,88695,88741,88742,84697,84698,88946,88947,88948,82404,88140,88143,88508,87252,87253,87254,87255,87256,87257,87258,87259,88102,88103,92203,92449,82551,82342,87890,82367,88943,88944,88945,92168)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
82342 Hudson Reed Slide Rail Kits Water Saving Slide Rail Kit - Chrome
82367 nuie Shower Kits Slider Rail Kit - Chrome
82404 Hudson Reed Slide Rail Kits Slider Rail Kit - Chrome / Black
82551 Rail for D Shaped Enclosure - Polished Chrome
84697 nuie Arno Compact 500mm Ceramic Basin 1 Tap Hole - White
84698 nuie Arno Compact 600mm Ceramic Basin 1 Tap Hole - White
87252 Old London Chancery Top Fix Soft Close Toilet Seat - Storm Grey
87253 Old London Richmond Top Fix Soft Close Toilet Seat - Storm Grey
87254 Old London Chancery Top Fix Soft Close Toilet Seat - Twilight Blue
87255 Old London Richmond Top Fix Soft Close Toilet Seat - Twilight Blue
87256 Old London Chancery Top Fix Soft Close Toilet Seat - Timeless Sand
87257 Old London Richmond Top Fix Soft Close Toilet Seat - Timeless Sand
87258 Old London Chancery Ryther Toilet Seat - Hunter Green
87259 Old London Richmond Carlton Toilet Seat - Hunter Green
87652 Hudson Reed 1700mm Straight Bath Front Panel & Plinth - Autumn Oak
87658 Hudson Reed 1700mm L Shape Square Shower Bath Front Panel - Autumn Oak
87666 Hudson Reed 1700mm Straight Bath Front Panel & Plinth - Graphite Grey
87672 Hudson Reed 1700mm L Shape Square Shower Bath Front Panel - Graphite Grey
87673 Hudson Reed 1700mm Straight Bath Front Panel & Plinth - Coastal Grey
87679 Hudson Reed 1700mm L Shape Square Shower Bath Front Panel - Coastal Grey
87680 Hudson Reed Havana Straight Shower Bath Front Panel & Plinth, 1700mm - Metallic Slate
87686 Hudson Reed Havana Square L Shape Shower Bath Front Panel & Plinth, 1700mm - Metallic Slate
87701 nuie 1700mm Straight Front Panel & Plinth - Solace Oak Woodgrain
87707 nuie 1700mm L Shape Square Shower Bath Front Panel - Solace Oak Woodgrain
87709 nuie 1700mm Straight Front Panel & Plinth - Anthracite Woodgrain
87721 nuie 1700mm L Shape Square Shower Bath Front Panel - Anthracite Woodgrain
87723 nuie 1700mm Straight Front Panel & Plinth - Charcoal Black Woodgrain
87735 nuie 1700mm L Shape Square Shower Bath Front Panel - Charcoal Black Woodgrain
87890 nuie Mayford Compact Cloakroom Cubix 1 Tap Hole Basin 480mm
88102 Hudson Reed Toilet Seats Chancery Toilet Seat - White
88103 Hudson Reed Toilet Seats Richmond Toilet Seat - White
88140 Old London 600mm Traditional Basin 1 Tap Hole
88143 Old London 600mm Traditional Basin 3 Tap Hole
88508 Furniture Minimalist Slimline Ceramic Basin 1 Tap Hole 800mm
88694 Hudson Reed Fusion L-Shape Shower Bath Front Panel 1700mm - Anthracite Woodgrain
88695 Hudson Reed Fusion Bath Front Panel & Plinth 1700mm - Anthracite Woodgrain
88741 Hudson Reed Fusion L-Shape Shower Bath Front Panel 1700mm - Hacienda Black
88742 Hudson Reed Fusion Bath Front Panel & Plinth 1700mm - Hacienda Black
88943 Hudson Reed Fusion Fitted Square Compact 1 Tap Hole Polymarble Basin 400mm
88944 Hudson Reed Fusion Fitted Square Compact 1 Tap Hole Polymarble Basin 500mm
88945 Hudson Reed Fusion Fitted Square Compact 1 Tap Hole Polymarble Basin 600mm
88946 Hudson Reed Fusion Fitted Square Full Depth 1 Tap Hole Polymarble Basin 400mm
88947 nuie Arno Compact 500mm Polymarble Basin 1 Tap Hole - White
88948 nuie Arno Compact 600mm Polymarble Basin 1 Tap Hole - White
91052 500 Classic Basin (540x410x185) 0TH
92168 BC Designs Flushpipe High Level Toilet Flush Pipe Kit - Chrome
92203 BC Designs Bath Wastes Push Down Exposed Bath Waste - Chrome
92449 BC Designs Push Down Freestanding Bath Waste - Chrome