A measurement of the effective $B^0_srightarrow K^+K^-$ lifetime is presented using approximately $37 pb^{-1}$ of data collected by LHCb during 2010. This quantity can be used to put constraints on contributions from processes beyond the Standard Mod
el in the $B^0_s$ meson system and is determined by two complementary approaches as $tau_{B^0_sto K^+K^-} = 1.440 pm 0.096 (stat) pm 0.008 (syst) pm 0.003 (model) ps$.
