You would need to schedule the microflow to run every 5 minutes.
At the start of your microflow you could check the time. If it's not in working hours, you could check the time to see if it matches your two-hour criteria - maybe by checking if the hour is divisible by 2, and the current minutes is 0. If it doesn't match, then drop out of the microflow before calling the API.
I hope this helps.