### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
if (roleDescriptor.hasRemoteIndicesPrivileges()) {
                    affectedRoles.add(roleDescriptor.getName());
                    return new RoleDescriptor(
                        roleDescriptor.getName(),
                        roleDescriptor.getClusterPrivileges(),
                        roleDescriptor.getIndicesPrivileges(),
                        roleDescriptor.getApplicationPrivileges(),
                        roleDescriptor.getConditionalClusterPrivileges(),
                        roleDescriptor.getRunAs(),
                        roleDescriptor.getMetadata(),
                        roleDescriptor.getTransientMetadata(),
                        null,
                        roleDescriptor.getRestriction()
                    );
                }
                return roleDescriptor;
            }).collect(Collectors.toSet());
            if (false == affectedRoles.isEmpty()) {
                logger.info(
                    "removed remote indices privileges from role(s) {} for API key(s) [{}]",
                    affectedRoles,
                    buildDelimitedStringWithLimit(10, apiKeyIds)
                );
                HeaderWarning.addWarning(
                    "Removed API key's remote indices privileges from role(s) "
                        + affectedRoles
                        + ". Remote indices are not supported by all nodes in the cluster. "
                        + "Use the update API Key API to re-assign remote indices to the API key(s), after the cluster upgrade is complete."
                );
            }