### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
final boolean success;
        final char[] hash;
        CachedApiKeyHashResult(boolean success, SecureString apiKey) {
            this.success = success;
            this.hash = cacheHasher.hash(apiKey);
        }
        boolean verify(SecureString password) {
            return hash != null && cacheHasher.verify(password, hash);
        }
    }
    public static final class ApiKeyDoc {
        private static final BytesReference NULL_BYTES = new BytesArray("null");
        static final InstantiatingObjectParser<ApiKeyDoc, Void> PARSER;
        static {
            InstantiatingObjectParser.Builder<ApiKeyDoc, Void> builder = InstantiatingObjectParser.builder(
                "api_key_doc",
                true,
                ApiKeyDoc.class
            );
            builder.declareString(constructorArg(), new ParseField("doc_type"));
            builder.declareField(
                optionalConstructorArg(),
                ApiKey.Type::fromXContent,
                new ParseField("type"),
                ObjectParser.ValueType.STRING