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 (
    89874, 89875, 89946, 89947, 91512, 91513, 
    82864, 82865, 82937, 82938, 83010, 
    83011, 83446, 83447, 83451, 83452, 
    82819, 82892, 82965, 86177, 86200, 
    86501, 86777, 84802
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00089

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "12.97"
    },
    "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": 24,
      "rows_produced_per_join": 24,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "10.57",
        "eval_cost": "2.40",
        "prefix_cost": "12.97",
        "data_read_per_join": "91K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (89874,89875,89946,89947,91512,91513,82864,82865,82937,82938,83010,83011,83446,83447,83451,83452,82819,82892,82965,86177,86200,86501,86777,84802)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
82819 nuie Arno 1200mm Wall Hung 2-Drawer Vanity & Worktop - Solace Oak
82864 nuie Arno 800mm Floor Standing 2-Drawer Vanity & Thin-Edge Basin - Solace Oak
82865 nuie Arno 800mm Floor Standing 2-Drawer Vanity & Curved Basin - Solace Oak
82892 nuie Arno 1200mm Wall Hung 2-Drawer Vanity & Worktop - Anthracite
82937 nuie Arno 800mm Floor Standing 2-Drawer Vanity & Thin-Edge Basin - Anthracite
82938 nuie Arno 800mm Floor Standing 2-Drawer Vanity & Curved Basin - Anthracite
82965 nuie Arno 1200mm Wall Hung 2-Drawer Vanity & Worktop - Charcoal Black
83010 nuie Arno 800mm Floor Standing 2-Drawer Vanity & Thin-Edge Basin - Charcoal Black
83011 nuie Arno 800mm Floor Standing 2-Drawer Vanity & Curved Basin - Charcoal Black
83446 nuie Athena Floor Standing 2 Drawer Vanity With Thin-Edge 1 Tap Hole Ceramic Basin 800mm - Anthracite Woodgrain
83447 nuie Athena Floor Standing 2 Drawer Vanity With Curved 1 Tap Hole Ceramic Basin 800mm - Anthracite Woodgrain
83451 nuie Athena Floor Standing 2 Drawer Vanity With Thin-Edge 1 Tap Hole Ceramic Basin 800mm - Hacienda Black
83452 nuie Athena Floor Standing 2 Drawer Vanity With Curved 1 Tap Hole Ceramic Basin 800mm - Hacienda Black
84802 nuie Classique Floor Standing 2 Door Vanity Basin Unit & 1 Tap Hole Fireclay Basin, 800mm - Satin White
86177 Hudson Reed Havana Wall Hung 2 Drawer Vanity Basin Unit & Mid-Edge Ceramic Basin, 600mm - Metallic Slate
86200 Hudson Reed Havana Wall Hung 2 Drawer Vanity Basin Unit & Mid-Edge Ceramic Basin, 600mm - Autumn Oak
86501 Hudson Reed Juno 600mm Wall Hung 2-Drawer Vanity & Mid-Edge 1 Tap Hole Basin - Autumn Oak
86777 Hudson Reed Juno Wall Hung 2 Drawer Vanity Basin Unit & Mid-Edge Ceramic Basin, 600mm - Metallic Slate
89874 Hudson Reed Urban Wall Hung 2 Drawer Vanity Unit with Thin-Edge Basin 800mm - Satin Blue
89875 Hudson Reed Urban Wall Hung 2 Drawer Vanity Unit with Curved Basin 800mm - Satin Blue
89946 Hudson Reed Urban 800mm Wall Hung 2-Drawer Unit and Thin-Edge Basin 1 Tap Hole - Satin Green
89947 Hudson Reed Urban 800mm Wall Hung 2-Drawer Unit and Curved Basin 1 Tap Hole - Satin Green
91512 Hudson Reed Urban Wall Hung 2 Drawer Vanity & Thin-Edge Ceramic Basin, 800mm - Satin Anthracite
91513 Hudson Reed Urban Wall Hung 2 Drawer Vanity & Curved Ceramic Basin, 800mm - Satin Anthracite