SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '47dc8d137dc645ff5074f013068c3cc9458bbc73db5d6b57986355951329a4f0' 
  AND token = 'm9Pg4ACOjdXtgFSV4MrSX4ZvtaE9djznpiIYOZN0ARU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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