### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
* @param apiKeyIds API key ids
     * @param withLimitedBy whether to parse and return the limited by role descriptors
     * @param listener listener for {@link GetApiKeyResponse}
     */
    public void getApiKeys(
        String[] realmNames,
        String username,
        String apiKeyName,
        String[] apiKeyIds,
        boolean withLimitedBy,
        ActionListener<GetApiKeyResponse> listener
    ) {
        ensureEnabled();
        findApiKeysForUserRealmApiKeyIdAndNameCombination(
            realmNames,
            username,
            apiKeyName,
            apiKeyIds,
            false,
            false,
            hit -> convertSearchHitToApiKeyInfo(hit, withLimitedBy),
            ActionListener.wrap(apiKeyInfos -> {
                if (apiKeyInfos.isEmpty()) {
                    logger.debug(
                        "No active api keys found for realms {}, user [{}], api key name [{}] and api key ids {}",
                        Arrays.toString(realmNames),
                        username,
                        apiKeyName,
                        Arrays.toString(apiKeyIds)
                    );