For your example, you could create an expression that looks like this:
[%CurrentDateTime%] > addHours([%BeginOfCurrentDay%], 7)
Which will evaluate true after 7am
The ‘problem’ with the the CurrentDateTime token: they will normally use the time zone of the server which is UTC. So if you want to be very specific about the current timezone and change to DST some moment, you will need some custom logic that will check the correct times based on the correct timezone.
You can then use [%BeginOfCurrentDayUTC%] to add or distract the correct amount of hours.
Ruuds answer is spot on how to do comparisons on available data in a microflow.
Please note that XPath is used for queries in the retrieve activity, page datasources etc.