You can definitely use CRA for production apps and not just for prototyping. If your needs are satisfied with the configuration they already provide out of the box then it gets even more easy for you as you don't need to figure out how webpack works and all that stuff.
If you are not satisfied (this was our case) go on and user thier eject feature and then roll your own configurations for webpack and other scripts. Also many people have a question that if they eject, do they lose all the commands it provides such as build, run etc ? The answer is NO. You still have those commands intact and they work as always except that now you can modify them easily and extend as required.
We for one are using CRA in prod after ejecting and there haven't been any issues :)