So i bought CK1050 rotary switch i now i realized that it's rated only for 150mA 250V AC/DC on the data sheet. I need to use it with 12V DC at 450mA so will it be safe? If you think the watts it should be safe 250V*0.15A=37.5W and 12V*0.45A=5.4W
You completely misunderstand the ratings. Power, as you calculate it, is irrelevant. All that matters is the current. You seem to want to switch 450 mA with a switch rated for 150 mA. So, no, you can't do it - or at least you can't do it too many times before it fails.
The only possible workaround is to turn off your power supply when switching. In this case, the load current will be zero when switching, and when the power supply comes back on, the non-switching limit (5 amps) will permit operation.