Navigate to the permission set to which you need grants to the custom page.

Then search and select the presentation object of the custom page (starting ‘cpg’) &

RMB on the custom page node and select ‘Grant Query’.

Then the users assigned with the above permission set will only be allowed to view the page content but not any CRUD operations.

http://ifstechdocs10.azurewebsites.net/foundation1/040_administration/210_security/020_permission_sets/040_presentation_object_grants/default.htm