A few quick code comments:

Now().UnixNano() is not guaranteed to be monotonically increasing. I'd be more careful if your keys really do need to be unique.

You can use time.Truncate to get the 10 minute interval.

    var t time.Time
    t = start
    for {
    	if t.After(stop) {
    		break
    	}
    	/* ... */
    	t = t.Add(d)
    }

Would usually be written:

    for t := start; !t.After(stop); t = t.Add(d) {