Token Content Access allows you to restrict access to individual entities using URL tokens. In order to view protected entities, users must provide a unique token via the URL.
This allows entities to be published and viewable to anonymous users (for instance with a special link from an email campaign) but not visible to the public at large.
Permissions are provided to administer each entity based module and to bypass the protection for all entities in that module.
Node protection is available in the included Token Content Access Nodes (tca_node) submodule and this can be used as a model to extend to other entities such as taxonomy terms, users, files and custom entities. It protects access to the node view page and also removes from Views, though that can be overridden on particular Views Displays. The token and protection status are available to include in a View, which supports both the use of contextual filters and being able to display the URL with token so an authorised user can copy it to share.
This module is designed with performance in mind, so it doesn't use traditional solutions like node grants. This also means that it's not guaranteed to block access in all situations, for instance, if you expose node content via means other than Views.