### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
}
        assertThat(cachedApiKeyDoc3.type, is(type));
        
        final String docId31 = randomAlphaOfLength(16);
        final String apiKey31 = randomAlphaOfLength(16);
        ApiKeyCredentials apiKeyCredentials31 = getApiKeyCredentials(docId31, apiKey31, ApiKey.Type.CROSS_CLUSTER);
        final Map<String, Object> metadata31 = mockKeyDocument(
            docId31,
            apiKey31,
            new User("stark", "superuser"),
            null,
            false,
            Duration.ofSeconds(3600),
            keyRoles,
            ApiKey.Type.CROSS_CLUSTER
        );
        service.loadApiKeyAndValidateCredentials(threadContext, apiKeyCredentials31, new PlainActionFuture<>());
        final ApiKeyService.CachedApiKeyDoc cachedApiKeyDoc31 = service.getDocCache().get(docId31);
        assertNotNull(cachedApiKeyDoc31);
        assertEquals("stark", cachedApiKeyDoc31.creator.get("principal"));
        
        assertEquals(3, service.getRoleDescriptorsBytesCache().count());
        
        assertThat(
            service.getRoleDescriptorsBytesCache().get(cachedApiKeyDoc31.limitedByRoleDescriptorsHash).utf8ToString(),
            equalTo("{}")
        );
        if (metadata31 == null) {
            assertNull(cachedApiKeyDoc31.metadataFlattened);
        } else {