### Description

The [Get API key information API](https://www.elastic.co/guide/en/elasticsearch/reference/master/security-api-get-api-key.html) can currently filter the returned keys by:
 * key id/name
 * keys owned by the calling user
 * keys owned by other users, by `realm_name` and `username`

Irrespective of the filtering used, both invalidated and expired (but not yet deleted) keys will be included in the response.
In the response, keys have the `invalidated` boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.

I propose we introduce a way for the API to support retrieving:
* only valid API keys (not return invalidated keys) - using a boolean request parameter
* keys not expired before a certain timestamp - using a timestamp parameter that defaults to "now" - also note that keys' experiation date is always checked against the local node's clock
x-pack/plugin/security/src/main/java/org/elasticsearch/xpack/security/authc/ApiKeyService.java
);
                return;
            }
            final IllegalArgumentException workflowsValidationException = validateWorkflowsRestrictionConstraints(
                transportVersion,
                request.getRoleDescriptors(),
                userRoleDescriptors
            );
            if (workflowsValidationException != null) {
                listener.onFailure(workflowsValidationException);
                return;
            }
            final Set<RoleDescriptor> filteredUserRoleDescriptors = maybeRemoveRemoteIndicesPrivileges(
                userRoleDescriptors,
                transportVersion,
                request.getId()
            );
            createApiKeyAndIndexIt(authentication, request, filteredUserRoleDescriptors, listener);
        }
    }
    private TransportVersion getMinTransportVersion() {
        return clusterService.state().getMinTransportVersion();
    }
    private static boolean hasRemoteIndices(Collection<RoleDescriptor> roleDescriptors) {
        return roleDescriptors != null && roleDescriptors.stream().anyMatch(RoleDescriptor::hasRemoteIndicesPrivileges);
    }
    private static IllegalArgumentException validateWorkflowsRestrictionConstraints(
        TransportVersion transportVersion,
        List<RoleDescriptor> requestRoleDescriptors,
        Set<RoleDescriptor> userRoleDescriptors