No-lag causal bandpass filter kernel formula
What you need is not a "no-lag" filter, as such a thing doesn't exist if the filter is still causal (how should it filter, without knowledge of the future and not being aloud to wait).

What you need is a filter with a constant group delay. Any linear phase filter has that. Any time-symmetric filter has linear phase. And by the simple method of shifting a time-symmetric filter by half its length, you make it causal. And have half its length in delay, at any frequency.

So, any filter kernel that is symmetric works. There's far too many bandpass filters that have linear phase, and which one you'd use completely depends on your application. But it's usually easier to find a tool to design a linear-phase filter than to find one that gives a different kind of filter, so you should be fine.