As others have posted, this is a very tight transfer for CMB if it involves checked baggage, a complete arrival clearance inbound and then a new outbound check in.

The recent terrorist attacks in Sri Lanka aren't relevant here, although its understandable this made you think about the process - this is purely about two separate tickets and the lack of time to get from one flight to another.

Agree with IAN-UK that an overnight (if this can be arranged) would be preferable if you can't get the Korean Airlines staff in MLE to interline the baggage through CMB onto the UL flight.