### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
Property.Dynamic
    );
    public static final Setting<String> CACHE_HASH_ALGO_SETTING = Setting.simpleString(
        "xpack.security.authc.api_key.cache.hash_algo",
        "ssha256",
        Setting.Property.NodeScope
    );
    public static final Setting<TimeValue> CACHE_TTL_SETTING = Setting.timeSetting(
        "xpack.security.authc.api_key.cache.ttl",
        TimeValue.timeValueHours(24L),
        Property.NodeScope
    );
    public static final Setting<Integer> CACHE_MAX_KEYS_SETTING = Setting.intSetting(
        "xpack.security.authc.api_key.cache.max_keys",
        25000,
        Property.NodeScope
    );
    public static final Setting<TimeValue> DOC_CACHE_TTL_SETTING = Setting.timeSetting(
        "xpack.security.authc.api_key.doc_cache.ttl",
        TimeValue.timeValueMinutes(5),
        TimeValue.timeValueMinutes(0),
        TimeValue.timeValueMinutes(15),
        Property.NodeScope
    );
    private final Clock clock;
    private final Client client;
    private final SecurityIndexManager securityIndex;
    private final ClusterService clusterService;
    private final Hasher hasher;
    private final boolean enabled;