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 (
    83347, 88245, 82591, 83354, 89781, 89828, 
    89829, 89880, 89881, 89952, 89953, 
    91518, 91519, 84882, 84897, 82574, 
    82575, 83161, 83162, 84672, 85015, 
    85021, 85027, 85033
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00037

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 (83347,88245,82591,83354,89781,89828,89829,89880,89881,89952,89953,91518,91519,84882,84897,82574,82575,83161,83162,84672,85015,85021,85027,85033)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
82574 nuie Arno 500mm Floor Standing 2-Door Vanity & Mid-Edge Basin - Gloss White
82575 nuie Arno 500mm Floor Standing 2-Door Vanity & Minimalist Basin - Gloss White
82591 nuie Arno 600mm Wall Hung 1-Drawer Vanity & Minimalist Basin - Gloss White
83161 nuie Athena Floor Standing 2 Door Vanity With Mid-Edge 1 Tap Hole Ceramic Basin 500mm - Gloss White
83162 nuie Athena Floor Standing 2 Door Vanity With Minimalist 1 Tap Hole Ceramic Basin 500mm - Gloss White
83347 nuie Athena Wall Hung Single Drawer Vanity With Sparkling White Worktop 600mm - Hacienda Black
83354 nuie Athena Wall Hung Single Drawer Vanity With Minimalist 1 Tap Hole Ceramic Basin 600mm - Gloss White
84672 Hudson Reed Fusion Wall Hung 1 Door Vanity Unit & Polymarble Basin 400mm - Gloss Grey
84882 nuie Core Floor Standing 2 Door Vanity Basin Unit & Ceramic Basin, 500mm - Satin Anthracite
84897 nuie Core Floor Standing 2 Door Vanity Basin Unit & Ceramic Basin, 500mm - Satin Green
85015 Hudson Reed Solar Floor Standing WC Unit 550mm - Pure White
85021 Hudson Reed Solar Floor Standing WC Unit 550mm - Cool Grey
85027 Hudson Reed Solar Floor Standing WC Unit 550mm - Indigo Blue
85033 Hudson Reed Solar 550mm Floor Standing WC Unit - Fern Green
88245 Hudson Reed Havana Wall Hung 2 Door Tall Unit, 350mm - Metallic Slate
89781 Hudson Reed Urban Floor Standing 2 Door Vanity Unit with Minimalist Basin 600mm - Satin White
89828 Hudson Reed Urban Floor Standing 2 Door Vanity Unit with Mid-Edge Basin 500mm - Satin Grey
89829 Hudson Reed Urban Floor Standing 2 Door Vanity Unit with Minimalist Basin 500mm - Satin Grey
89880 Hudson Reed Urban Floor Standing 2 Door Vanity Unit with Mid-Edge Basin 500mm - Satin Blue
89881 Hudson Reed Urban Floor Standing 2 Door Vanity Unit with Minimalist Basin 500mm - Satin Blue
89952 Hudson Reed Urban 500mm Floor Standing 2-Door Vanity and Mid-Edge Basin 1 Tap Hole - Satin Green
89953 Hudson Reed Urban 500mm Floor Standing 2-Door Vanity and Minimalist Basin 1 Tap Hole - Satin Green
91518 Hudson Reed Urban Floor Standing 2 Door Vanity & Mid-Edge Ceramic Basin, 500mm - Satin Anthracite
91519 Hudson Reed Urban Floor Standing 2 Door Vanity & Minimalist Ceramic Basin, 500mm - Satin Anthracite