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 (
    85868, 85870, 85871, 85568, 85544, 84237, 
    85548, 85558, 92838, 92839, 92895, 
    92896, 92897, 92898, 92899, 92900, 
    92901, 92902, 92903, 92904, 92905, 
    92906, 92907, 92908
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00065

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 (85868,85870,85871,85568,85544,84237,85548,85558,92838,92839,92895,92896,92897,92898,92899,92900,92901,92902,92903,92904,92905,92906,92907,92908)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}