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 (
    92344, 88925, 88926, 88927, 91470, 91884, 
    91900, 90844, 82430, 82431, 82433, 
    91896, 90272, 86076, 86079, 86080, 
    90794, 90271, 90795, 86077, 86078, 
    93868, 93869, 93870
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00038

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 (92344,88925,88926,88927,91470,91884,91900,90844,82430,82431,82433,91896,90272,86076,86079,86080,90794,90271,90795,86077,86078,93868,93869,93870)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
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
86076 nuie Pacific Square Handle - Chrome
86077 nuie Ella Rounded Handle - Chrome
86078 nuie Ella Square Handle - Chrome
86079 nuie Pacific Square Handle - Black
86080 nuie Pacific Single Handle SQ/ - 145mm Centres - Chrome
88925 nuie 1850mm Profile Extension Kit - Chrome
88926 nuie 1850mm Profile Extension Kit - Matt Black
88927 Hudson Reed 1900mm Profile Extension Kit - Polished Chrome
90271 nuie Wetroom Wall Channel 1850mm - Brushed Brass
90272 Return Screen L Profile Kit 1850mm Black - Brushed Brass
90794 Hudson Reed Apex Handle - Chrome
90795 Hudson Reed Apex Handle - Chrome
90844 nuie Pacific Enclosure Screw Cover Kit Chrome, 1850mm - Chrome
91470 nuie Pacific Enclosure Profile Extension Kit, 1850mm - Brushed Brass
91884 BC Designs Victrion 3 Tier Shower Tidy - Chrome
91896 BC Designs Victrion Corner Shower Basket - Chrome
91900 BC Designs Victrion Double Corner Shower Basket - Chrome
92344 BC Designs Victrion Corner Shower Basket - Brushed Nickel
93868
93869
93870