We investigate the possibility of scalar interaction affecting the forward backward asymmetry in the decay mode $B\to K \mu^+ \mu^-$. Using the scalar contribution and advocating Cheng-Sher type ansatz we obtain sizable forward backward asymmetry. Furthermore, we study the effect of the scalar interaction in $K^+ \to \pi^+ \mu^+ \mu^-$. It is pointed out that non-zero forward backward asymmetry in $B\to K l^+ l^-$, if found in future B-factories, may indicate the new physics in the scalar sector.
Comment: 11 pages, 3 figures, version to appear in Phys. Letter. B