That will only work if its exactly at 15:00:00. Typically you’d need to template this. Or if you don’t want to template it, these conditions technically match what you want:
condition:
- condition: or
conditions:
- condition: time
before: "15:00:00"
- condition: time
after: "15:01:00"
This is identical to saying “time does not equal 15:00:00”, assuming you want it to span the entire minute. If you want it to span only that second:
condition:
- condition: or
conditions:
- condition: time
before: "15:00:00"
- condition: time
after: "15:00:01"