Closure to be screwed onto a container

A closure to be screwed onto a container, comprising:

• a closure cap and a screw cap that can be twisted together with each other as well as relative to each other, the closure cap including a support element that is screwed to the screw cap, whereby the closure cap and the screw cap define a chamber that holds a substance and that is opened by twisting the screw cap relative to the closure cap, thereby opening up at least one passage that is in communication with the container, wherein the screw cap has a chamber wall whose free end surrounds a chamber bottom formed in the closure cap and a lid section onto which the chamber wall is formed,
• wherein the screw cap and the support element of the closure cap are locked by at least one thread locking mechanism configured as a spring-loaded finger located in an outer thread of the support element and that, under elastic pre-tensioning, is laid with its blocking surface against an inner thread of the screw cap such that after a few twists of the screw cap relative to the closure cap, further relative twisting of the screw cap is blocked.