Filtering by date in a bespoke table that has no date

I'm trying to create a query containing everyone who did a certain action on our website.

That data is in its own schema.  Unfortunately, there is no date written to that schema as to when this action happened.

Is there a system date that I can use (Date Record Added or something) to filter on this value?  I only need the query to contain these actions from the last 3 days.  Currently the query is taking a long time to load as it's pulling in everyone who did the action.

Thanks, Tom