Answer
No — a Custom Event fundamentally requires some genuine trigger point, a database change, to fire at all, even for a workflow-style use case, so there's no way to have a Custom Event run purely on a schedule with no underlying data-change trigger. For a purely time-based, SQL-query-driven requirement like this, two real options exist: (1) a customization creating a dedicated utility function registered and scheduled as a Database Task, giving full programmatic control; or (2), the simpler and generally preferable option since the requirement is fundamentally just a SQL query on a schedule, build it as a Scheduled Quick Report instead, configured to run automatically at the desired interval and email its generated output directly to the relevant users, avoiding the need for a Custom Event or a full custom Database Task at all.