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 (
    82430, 82431, 82433, 82558, 87387, 87389, 
    85575, 85579, 82372, 86889, 86895, 
    82359, 87383, 87384, 87385, 89612, 
    89613, 91896, 87888, 91844, 88932, 
    92185, 92382, 85561
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00060

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 (82430,82431,82433,82558,87387,87389,85575,85579,82372,86889,86895,82359,87383,87384,87385,89612,89613,91896,87888,91844,88932,92185,92382,85561)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
82359 Large Traditional Handset
82372 nuie Shower Accessories Outlet Elbow - Chrome
82430 nuie Enclosure Hook For Frameless Enclosures - Chrome
82431 nuie Enclosure Hook For Framed Enclosures - Chrome
82433 nuie Enclosure Hook For Frameless Enclosures - Smoked Black
82558 nuie Wall-Mounted Arm - Chrome
85561 Retainer Bath Waste Brass & Link Chain
85575 nuie Wastes & Extras Pop Up Bath Waste - Chrome
85579 nuie Heating Accessories Decorative Chrome Pipes - Chrome
86889 Traditional Towel Ring
86895 Traditional Toilet Roll Holder
87383 nuie Ceramics Accessories Square Dual Flush Black Push Button -
87384 nuie Ceramics Accessories Square Dual Flush Brushed Brass Push Button -
87385 nuie Square Dual Flush Push Button - Gun Metal
87387 nuie Ceramics Accessories Round Flush Plate for Pneumatic Dual Flush - Matt Black
87389 nuie Ceramics Accessories Round Flush Plate for Pneumatic Dual Flush - Matt White
87888 nuie Baths Leg Set
88932 Hudson Reed Shower Accessories Brass Pencil Handset - Chrome
89612 nuie Ceramics Accessories Dual Flush Button - Black
89613 nuie Ceramics Accessories Dual Flush Button - Brushed Brass
91844 BC Designs Victrion Dog Bone Toilet Roll Holder with Back Plate - Chrome
91896 BC Designs Victrion Corner Shower Basket - Chrome
92185 BC Designs Bath Wastes Plug & Chain Concealed Bath Waste - Chrome
92382 BC Designs Lever Handle for Close Coupled/Low Level Cistern - Chrome/White