Blaupunkt 4k LED TV as external monitor for MBP mid 2012 retina issue
Your system supports following resolutions:

You can use 4K displays and Ultra HD TVs at the following resolutions and refresh rates via the built-in HDMI port.

3840 x 2160 at 30 Hz refresh rate

4096 x 2160 at 24 Hz refresh rate (mirroring is not supported at this resolution)- MBP 2013 and up.


Thus no 60Hz is possible.