If you have access to priority check-in and security, 90 minutes is plenty, otherwise it might be very tight, but looking at the MCT, and considering your flight is therefore in winter, it's probably still fine.
If your train is delayed, I'm sure KL will take care of you.
The MCT, for reference, is:
Code:
KL-KL II 2.00 EQP TRN - ALL OPN -31OCT17
KL-KL II 1.30 EQP TRN - ALL 01NOV17-INF