This work is concerned with the proof of $L_p-L_q$ decay estimates for solutions of the Cauchy problem for the Klein-Gordon type equation $u_{tt}-{\lambda }^2\left(t\right)b^2\left(t\right)(\Delta u-m^{2}u)=0$. The coefficient consists of an increasing smooth function $\lambda$ and an oscillating smooth and bounded function b which are uniformly separated from zero. Moreover, $m^2$ is a positive constant. We study under which assumptions for λ and b one can expect as an essential part of the decay rate the classical Klein-Gordon decay rate n/2(1/p-1/q).