SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0155d76dcd42d39cc7d7d5887b7e71d27af6fee8247fa4f184321628a2d49bcc' 
  AND token = 'cDfJC9xRqHis/mwujsXypGC/e2qYxqXTEmUY1QC8VZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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