Chebyshev bound from a moment generating function

Let $X$ be a random variable with the moment generating function

$$M_X(t)=\left(\frac{e^{\frac t2}+e^{-\frac t2}}{2}\right)^2,\quad -\infty<t<\infty.$$

Using Chebyshev's inequality, the upper bound for $P\left(|X|>\sqrt{\frac23}\right)$ equals ___________