It is possible to write a(n iterative) macro in Alteryx, with the help of the CReW Macros, that checks a table for some condition then continues if it's true or pauses and tries again if it is not true.
I've made a workflow with such a macro that checks the maximum value of a date column against the max from a Modified field in a SharePoint list and only ran an update workflow if the SharePoint value ever became greater or equal to the one in the db.
The trick at that point is to match the maximum iteration time to the workflow's schedule. So if you have the pause tool wait for 5s and you have a max of 60 iterations, you can schedule the job to run every 5 min. In this case, at most, you'll have a sub-5-minute window where the source isn't being checked.