mappi,

Yes it's carnatic style - predominantly. The raga being dwijavanthi/jaijaivanthi, the hindustani touches also appear. (Film songs-la ithellaam saatharanamappa.) I think the instrument is nadhaswaram - not shenai. Note that the song is about marriage vows.

I am not sure why you think it's about krishna lullaby. May be it's just the raga that has such a feel. You may want to check out 'akilandeswari' (esp. the one by MSS.) and confirm yourself.

Cheers..