> I only took this job in order to buy some time and create some interesting things but this job barely leaves me any time to do so.

If your interest is in creating "interesting things," you should focus on the ways you can scratch this itch. If you go into your next job looking to "buy some time" you probably won't be any happier than you are now.

> I feel I should know modern frameworks like Rails and Angular to have a better appeal...

Software development is software development.

A lot of jobs, even at prominent/"hot" companies, primarily involve CRUD applications and mundane development tasks ("grunt work"). Proficiency in Rails or Angular might help you land a new job, but it's worth contemplating the very real possibility that the nature of the work at these companies won't be any more engaging to you just because your employer uses a framework du jour.