### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
}
        sourceMap.put("creation_time", Clock.systemUTC().instant().toEpochMilli());
        sourceMap.put("expiration_time", -1);
        sourceMap.put("api_key_hash", new String(hash));
        sourceMap.put("name", randomAlphaOfLength(12));
        sourceMap.put("version", 0);
        sourceMap.put("role_descriptors", Collections.singletonMap("a role", Collections.singletonMap("cluster", List.of("all"))));
        sourceMap.put(
            "limited_by_role_descriptors",
            Collections.singletonMap("limited role", Collections.singletonMap("cluster", List.of("all")))
        );
        Map<String, Object> creatorMap = new HashMap<>();
        creatorMap.put("principal", "test_user");
        creatorMap.put("full_name", "test user");
        creatorMap.put("email", "test@user.com");
        creatorMap.put("metadata", Collections.emptyMap());
        sourceMap.put("creator", creatorMap);
        sourceMap.put("api_key_invalidated", false);
        
        sourceMap.put("metadata_flattened", ApiKeyTests.randomMetadata());
        return sourceMap;
    }
    private void mockSourceDocument(String id, Map<String, Object> sourceMap) throws IOException {
        try (XContentBuilder builder = JsonXContent.contentBuilder()) {
            builder.map(sourceMap);
            SecurityMocks.mockGetRequest(client, id, BytesReference.bytes(builder));
        }
    }
    private ApiKeyDoc buildApiKeyDoc(char[] hash, long expirationTime, boolean invalidated) throws IOException {
        return buildApiKeyDoc(hash, expirationTime, invalidated, randomAlphaOfLength(12));