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 (
    90831, 88191, 88203, 87536, 88399, 88493, 
    84768, 84781, 84790, 87503, 87519, 
    88442, 88459, 88476, 88521, 89838, 
    89890, 89962, 88445, 84763, 89103, 
    89111, 90830, 89786, 89836, 89888, 
    89960, 87535, 88398, 88491, 88443, 
    90816, 89018, 89784, 87616, 87624, 
    90815, 89102, 89110, 90829, 89017, 
    88547, 87620, 87622, 88543, 89016
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00068

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "20.72"
    },
    "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": 46,
      "rows_produced_per_join": 46,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.13",
        "eval_cost": "4.60",
        "prefix_cost": "20.73",
        "data_read_per_join": "175K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (90831,88191,88203,87536,88399,88493,84768,84781,84790,87503,87519,88442,88459,88476,88521,89838,89890,89962,88445,84763,89103,89111,90830,89786,89836,89888,89960,87535,88398,88491,88443,90816,89018,89784,87616,87624,90815,89102,89110,90829,89017,88547,87620,87622,88543,89016)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}