### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
) {
        assert request.getType() != ApiKey.Type.CROSS_CLUSTER || false == authentication.isApiKey()
            : "cannot create derived cross-cluster API keys";
        assert request.getType() != ApiKey.Type.CROSS_CLUSTER || userRoleDescriptors.isEmpty()
            : "owner user role descriptor must be empty for cross-cluster API keys";
        ensureEnabled();
        if (authentication == null) {
            listener.onFailure(new IllegalArgumentException("authentication must be provided"));
        } else {
            final TransportVersion transportVersion = getMinTransportVersion();
            if (transportVersion.before(TRANSPORT_VERSION_ADVANCED_REMOTE_CLUSTER_SECURITY_CCS)
                && hasRemoteIndices(request.getRoleDescriptors())) {
                
                listener.onFailure(
                    new IllegalArgumentException(
                        "all nodes must have transport version ["
                            + TRANSPORT_VERSION_ADVANCED_REMOTE_CLUSTER_SECURITY_CCS
                            + "] or higher to support remote indices privileges for API keys"
                    )
                );
                return;
            }
            if (transportVersion.before(TRANSPORT_VERSION_ADVANCED_REMOTE_CLUSTER_SECURITY_CCR)
                && request.getType() == ApiKey.Type.CROSS_CLUSTER) {
                listener.onFailure(
                    new IllegalArgumentException(
                        "all nodes must have transport version ["
                            + TRANSPORT_VERSION_ADVANCED_REMOTE_CLUSTER_SECURITY_CCR
                            + "] or higher to support creating cross cluster API keys"
                    )