### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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/test/java/org/elasticsearch/xpack/security/authc/ApiKeyServiceTests.java
),
                XContentType.JSON
            )
        );
        final boolean changeUserRoles = type != ApiKey.Type.CROSS_CLUSTER && randomBoolean();
        final boolean changeKeyRoles = randomBoolean();
        final boolean changeMetadata = randomBoolean();
        final boolean changeVersion = randomBoolean();
        final boolean changeCreator = randomBoolean();
        final Set<RoleDescriptor> newUserRoles = changeUserRoles
            ? randomValueOtherThan(oldUserRoles, () -> randomSet(0, 3, RoleDescriptorTests::randomRoleDescriptor))
            : oldUserRoles;
        final List<RoleDescriptor> newKeyRoles;
        if (changeKeyRoles) {
            if (type == ApiKey.Type.CROSS_CLUSTER) {
                newKeyRoles = randomValueOtherThan(oldKeyRoles, () -> {
                    try {
                        return List.of(CrossClusterApiKeyRoleDescriptorBuilder.parse(randomCrossClusterApiKeyAccessField()).build());
                    } catch (IOException e) {
                        throw new UncheckedIOException(e);
                    }
                });
            } else {
                newKeyRoles = randomValueOtherThan(oldKeyRoles, () -> randomList(0, 3, RoleDescriptorTests::randomRoleDescriptor));
            }
        } else {
            newKeyRoles = randomBoolean() ? oldKeyRoles : null;
        }
        final Map<String, Object> newMetadata = changeMetadata
            ? randomValueOtherThanMany(md -> md == null || md.equals(oldMetadata), ApiKeyTests::randomMetadata)