Every instrument can be difficult in the beginning, and due to all the different types of keyboard there is no clear cut answer. A keyboard can refer to multiple different items - if you want to play a digital piano, it would take the same amount of time and care as with an acoustic. If you are looking to use a MIDI controller to produce music, this can take less time and be easier dependent on how skilled you want to be. There are also other options. As with any musical instrument, it takes practise!