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 (
    86477, 86478, 86753, 86754, 84511, 84577, 
    88782, 86634, 86703, 87401, 89993, 
    88983, 84495, 84561, 83155, 83160, 
    82602, 84294, 88778, 88779, 89841, 
    89893, 89966, 91532, 82818, 82891, 
    82964, 83338, 83348, 84880, 84895, 
    87399, 82588, 82589, 84869, 84538, 
    84604, 89212, 89225, 89238, 90005, 
    82826, 82899, 82972, 84868, 85666, 
    85686, 85698
  ) 
  AND cscart_product_descriptions.lang_code = 'en'

Query time 0.00072

JSON explain

{
  "query_block": {
    "select_id": 1,
    "cost_info": {
      "query_cost": "21.63"
    },
    "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": 48,
      "rows_produced_per_join": 48,
      "filtered": "100.00",
      "cost_info": {
        "read_cost": "16.83",
        "eval_cost": "4.80",
        "prefix_cost": "21.63",
        "data_read_per_join": "183K"
      },
      "used_columns": [
        "product_id",
        "lang_code",
        "short_description",
        "full_description"
      ],
      "attached_condition": "((`nuie_scalesta_net`.`cscart_product_descriptions`.`product_id` in (86477,86478,86753,86754,84511,84577,88782,86634,86703,87401,89993,88983,84495,84561,83155,83160,82602,84294,88778,88779,89841,89893,89966,91532,82818,82891,82964,83338,83348,84880,84895,87399,82588,82589,84869,84538,84604,89212,89225,89238,90005,82826,82899,82972,84868,85666,85686,85698)) and (`nuie_scalesta_net`.`cscart_product_descriptions`.`lang_code` = 'en'))"
    }
  }
}