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 (
    86518, 86650, 86719, 86793, 86794, 82837, 
    82910, 82983, 83397, 83407, 86140, 
    86163, 86648, 86717, 84818, 84819, 
    91155, 82844, 82845, 82917, 82918, 
    82990, 82991, 83474
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00071

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "10.82"
    },
    "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": "8.42",
        "eval_cost": "2.40",
        "prefix_cost": "10.82",
        "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 (86518,86650,86719,86793,86794,82837,82910,82983,83397,83407,86140,86163,86648,86717,84818,84819,91155,82844,82845,82917,82918,82990,82991,83474)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
82837 nuie Arno 600mm Wall Hung 2-Drawer Vanity & Laminate Top - Solace Oak
82844 nuie Arno 800mm Wall Hung 1-Drawer Vanity & Thin-Edge Basin - Solace Oak
82845 nuie Arno 800mm Wall Hung 1-Drawer Vanity & Curved Basin - Solace Oak
82910 nuie Arno 600mm Wall Hung 2-Drawer Vanity & Laminate Top - Anthracite
82917 nuie Arno 800mm Wall Hung 1-Drawer Vanity & Thin-Edge Basin - Anthracite
82918 nuie Arno 800mm Wall Hung 1-Drawer Vanity & Curved Basin - Anthracite
82983 nuie Arno 600mm Wall Hung 2-Drawer Vanity & Laminate Top - Charcoal Black
82990 nuie Arno 800mm Wall Hung 1-Drawer Vanity & Thin-Edge Basin - Charcoal Black
82991 nuie Arno 800mm Wall Hung 1-Drawer Vanity & Curved Basin - Charcoal Black
83397 nuie Athena Wall Hung 2 Drawer Vanity With Grey Worktop 600mm - Anthracite Woodgrain
83407 nuie Athena Wall Hung 2 Drawer Vanity With Grey Worktop 600mm - Hacienda Black
83474 nuie Athena Wall Hung Single Drawer Vanity With Thin-Edge 1 Tap Hole Ceramic Basin 800mm - Anthracite Woodgrain
84818 nuie Classique Wall Hung 1 Drawer Vanity Basin Unit & 1 Tap Hole Fireclay Basin, 600mm - Satin White
84819 nuie Classique Wall Hung 1 Drawer Vanity Basin Unit & 3 Tap Hole Fireclay Basin, 600mm - Satin White
86140 Hudson Reed Havana Wall Hung 2 Drawer Unit & Colour Match Worktop, 600mm - Graphite Grey
86163 Hudson Reed Havana Wall Hung 2 Drawer Unit & Colour Match Worktop, 600mm - Coastal Grey
86518 Hudson Reed Juno 800mm Wall Hung Single Drawer Vanity & Laminate Top - Autumn Oak
86648 Hudson Reed Juno 600mm Wall Hung 2-Drawer Vanity & Worktop - Graphite Grey
86650 Hudson Reed Juno 800mm Wall Hung Single Drawer Vanity & Mid-Edge 1 Tap Hole Basin - Graphite Grey
86717 Hudson Reed Juno 600mm Wall Hung 2-Drawer Vanity & Worktop - Coastal Grey
86719 Hudson Reed Juno 800mm Wall Hung Single Drawer Vanity & Mid-Edge 1 Tap Hole Basin - Coastal Grey
86793 Hudson Reed Juno Wall Hung 1 Drawer Vanity Unit & Laminate Worktop, 800mm - Metallic Slate/Sparkle Black
86794 Hudson Reed Juno Wall Hung 1 Drawer Vanity Unit & Laminate Worktop, 800mm - Metallic Slate/Sparkle White
91155 nuie Classique Wall Hung 1 Drawer Unit & 0 Tap Hole Fireclay Basin, 600mm - Satin White