1 hour and 40 minutes connecting Schengen-Schengen in CPH is normally plenty of time, there will be no passport control until you reach AMS. Having no checked luggage means you do not need to exit landside to check-in, check in can be done online (i.e. whilst still in PRG). In the worst case scenario you would need about 20 minutes in the terminal at CPH (For walking between A and C gates). The Czech Airlines flight is out of its hub in the morning and the flight in May so I'd say that the risk of a delay that would make you miss the CPH-AMS flight is quite small.