This would qualify as a very tight connection even during normal times, as check in for your CMB - MCT flight would close literally 15 mins after you land in CMB. I have done the transfer in CMB on separate tickets numerous times in the past (collect bags exit & re-check in) and it takes at least 20 mins. I'm expecting higher wait times and increases security checks in light of recent events.
You could try to approach the transfer desk at CMB airport that's manned by Sri Lankan Airlines staff & if your only with hand luggage as other have recommended, then you could possibly make it.
Else the other option being, as IAN-UK has suggested; breaking journey in CMB for a night. This would involve a ticket change though