Mo. Rev. Stat. § 506.375: Dismissal of action, when.

Notwithstanding any court costs which have been paid, the court shall dismiss an offender's civil action or appeal from a judgment in a civil action at any time, including before service on the defendant, if the court determines any of the following:

(1) The allegation of indigency is untrue;

(2) The litigation is frivolous, malicious or fails to state a claim upon which relief may be granted; or

(3) The defendant is immune from the cause of action.