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 (
    88930, 90107, 90080, 89526, 90064, 89641, 
    91298, 83106, 91305, 84112, 89488, 
    91306, 91301, 83112, 83122, 83132, 
    89624, 90066, 86384, 89618, 89631, 
    89625, 89638, 89634, 89726, 90091, 
    90101, 90078, 85533, 89015
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "13.52"
    },
    "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": 30,
      "rows_produced_per_join": 30,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.52",
        "eval_cost": "3.00",
        "prefix_cost": "13.52",
        "data_read_per_join": "114K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (88930,90107,90080,89526,90064,89641,91298,83106,91305,84112,89488,91306,91301,83112,83122,83132,89624,90066,86384,89618,89631,89625,89638,89634,89726,90091,90101,90078,85533,89015)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
83106 nuie Arvan Wall Mounted 3 Tap Hole Basin Mixer With Plate - Chrome
83112 nuie Arvan Wall Mounted 2 Tap Hole Basin Mixer With Plate - Matt Black
83122 nuie Arvan Wall Mounted 2 Tap Hole Basin Mixer With Plate - Gunmetal
83132 nuie Arvan High-Rise Mono Basin Mixer (No Waste) - Brushed Brass
84112 nuie Binsey Wall Mounted 3 Tap Hole Basin Mixer With Plate - Chrome
85533 Hudson Reed Drift Wall Plated Single Lever Basin Mixer - Chrome
86384 nuie Beaumont 3 Tap Hole Basin Mixer - Chrome
88930 Hudson Reed Tec Single Lever Wall Mounted Basin Bath Filler - Chrome
89015 Hudson Reed Tec Single Lever Mono Basin Mixer - Brushed Brass
89488 Hudson Reed Soar Wall Plated Single Lever Basin Mixer - Chrome
89526 Hudson Reed Sottile Wall Plated Single Lever Basin Mixer - Chrome
89618 Hudson Reed Tec Lever 3 Tap Hole Basin Mixer - Chrome
89624 Hudson Reed Tec Lever Mono Basin Mixer - Brushed Brass
89625 Hudson Reed Tec Lever Wall Mounted Basin Mixer - Brushed Brass
89631 Hudson Reed Tec Crosshead 3 Tap Hole Basin Mixer - Chrome
89634 Hudson Reed Tec Crosshead Mono Basin Mixer - Matt Black
89638 Hudson Reed Tec Crosshead Wall Mounted Basin Mixer - Brushed Brass
89641 Hudson Reed Revolution Mono Basin Mixer - Chrome
89726 nuie Vibe High Rise Mixer - Chrome
90064 Hudson Reed Willow Wall Plated Single Lever Basin Mixer - Chrome
90066 Hudson Reed Willow Tall Mono Basin Mixer - Chrome
90078 nuie Windon Wall Mounted 3 Tap Hole Basin Mixer - Chrome
90080 nuie Windon Wall Mounted 2 Tap Hole Basin Mixer With Plate - Chrome
90091 nuie Windon High-Rise Mono Basin Mixer (No Waste) - Matt Black
90101 nuie Windon High-Rise Mono Basin Mixer (No Waste) - Gunmetal
90107 nuie Windon Mono Basin Mixer With Push Button Waste - Brushed Brass
91298 nuie Aztec Deck Mount 3 Tap Hole Basin Mixer - Chrome
91301 nuie Aztec Deck Mount Mono Basin Mixer Tap with Push Button Waste - Matt Black
91305 nuie Aztec Deck Mount Mono Basin Mixer Tap with Push Button Waste - Brushed Brass
91306 nuie Aztec Wall Mount 3 Tap Hole Basin Mixer - Brushed Brass