If you can sustain a high percentage of your anaerobic threshold (AT), then that's a "good" HR. It actually does show that you're in good shape.
Where that AT is, is the tricky part. Although we sometimes see it as a percentage of the maximum HR, that's basically a fiction utilized by writers (internet coaches?) to simplify things. The reality is that the maximum HR doesn't really say much about it. In a general range, sure but specifically no. Our AT can be increased with enough specific training (increasing VO2max, the maximum amount of oxygen we can take in and utilize), but the goal for most of us, usually, is training how well we can sustain something closer to the AT.