That is why for Callbacks we have 2 'trigger' options. Generally if your Maximum Queue Wait time is 90 seconds, there is no point in having callback enabled.
Idea #1:
Set the Max Queue Wait time to something larger, like 10-15 minutes, then set the callback to 90 seconds.
Idea #2:
If you want to keep the Max Wait Time at 90 seconds, disable callback completely. Then build your own
Call Flow Designer App that prompts external callers for their "Callback number" and then sends this information to an email distribution group that contains the Queue Agents emails.
The use-case of this would be to set the "Destination if no answer" of the Queue to the Call Flow App.