you can use the construct 3 date plugin to compare the time/date. construct.net/en/make-games/manuals/construct-3/plugin-reference/date
If a reward is claimed store that state in a variable that is saved (using whatever method of saving you are using) and have that variable reset to unclaimed on game load, or during play, if the time is after 00:00 on the next day.
Of course this only compares system time which can be exploited. If you are happy with your players requiring an internet connection you can get the date/time from a server online.