Cruise missiles usually features low RCS on avarage. But some are optimized for better stealth like JASSM, KH-101, JSM, SCALP or SOM.
But the thing is, when they arrived over the horizon, (30-40km away) today's sensors (That include IRSTs) are so sensitive no matter how low your RCS is, at some point you can't mask your self anymore.
Easy way to think about this is, if a stealth 5th gen fighter like F-35 can get caught from 50-60km by new gen AESA, JASSM can’t hide for too long either.
And then let's not forget, how slow subsonic cruise missiles are.
Let's say if it got detected from 20-30km away (conservative estimate) AD system would have engagement window of 60-90 seconds.
And for a modern AD systems that can react in less then 10 seconds and guide 16-24 interceptors to the targets simultaneously, it is big fat window of engagement.