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 (
    92176, 92177, 92178, 92322, 92323, 92324, 
    92161, 92162, 92163, 92164, 92165, 
    92166, 84712, 84711, 84710, 84940, 
    84728, 84729, 84730, 84731, 84732, 
    84733, 84720, 84723
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00093

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 (92176,92177,92178,92322,92323,92324,92161,92162,92163,92164,92165,92166,84712,84711,84710,84940,84728,84729,84730,84731,84732,84733,84720,84723)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}

Result

product_id short_description full_description
84710 Hudson Reed Maya 550mm Basin & Pedestal
84711 Hudson Reed Maya 650mm Basin & Pedestal
84712 Hudson Reed Maya 850mm Basin & Pedestal
84720 Old London Richmond 600mm Basin & Pedestal 1 Tap Hole
84723 Old London Richmond 600mm Basin & Pedestal 2 Tap Hole
84728 Old London Richmond 600mm 3 Tap Hole Basin & Comfort Height Pedestal
84729 Old London Richmond 600mm 2 Tap Hole Basin & Comfort Height Pedestal
84730 Old London Richmond 600mm 1 Tap Hole Basin & Comfort Height Pedestal
84731 Old London Richmond 560mm 3 Tap Hole Basin & Comfort Height Pedestal
84732 Old London Richmond 560mm 2 Tap Hole Basin & Comfort Height Pedestal
84733 Old London Richmond 560mm 1 Tap Hole Basin & Comfort Height Pedestal
84940 Hudson Reed Arlo 550mm Basin & Pedestal
92161 BC Designs Victrion 640mm Basin & Pedestal 1TH - White
92162 BC Designs Victrion 640mm Basin & Pedestal 2TH - White
92163 BC Designs Victrion 640mm Basin & Pedestal 3TH - White
92164 BC Designs Victrion 640mm Basin & Pedestal 1TH - White
92165 BC Designs Victrion 640mm Basin & Pedestal 2TH - White
92166 BC Designs Victrion 640mm Basin & Pedestal 3TH - White
92176 BC Designs Victrion 640mm Basin & Ornate Stand 1TH - White
92177 BC Designs Victrion 640mm Basin & Ornate Stand 2TH - White
92178 BC Designs Victrion 640mm Basin & Ornate Stand 3TH - White
92322 Nuie Classique 500mm 1TH Basin & Luxury Washstand
92323 Nuie Classique 500mm 0TH Basin & Luxury Washstand
92324 Nuie Classique 500mm 3TH Basin & Luxury Washstand