SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '544e8bc6b1c9d24799583a6df9231852485a56f2daaaec67f96d008d56a41089' 
  AND token = 'r4qJTUGHF+cs5USPG/FAtIjVRG9vKegzQkwQt94QPPE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00051

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}