### 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boolean property, as well as the `expiration` property that contains the UNIX timestamp past of which the key is no longer valid for authentication.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
);
            builder.declareLong(constructorArg(), new ParseField("creation_time"));
            builder.declareLongOrNull(constructorArg(), -1, new ParseField("expiration_time"));
            builder.declareBoolean(constructorArg(), new ParseField("api_key_invalidated"));
            builder.declareString(constructorArg(), new ParseField("api_key_hash"));
            builder.declareStringOrNull(optionalConstructorArg(), new ParseField("name"));
            builder.declareInt(constructorArg(), new ParseField("version"));
            ObjectParserHelper.declareRawObject(builder, constructorArg(), new ParseField("role_descriptors"));
            ObjectParserHelper.declareRawObject(builder, constructorArg(), new ParseField("limited_by_role_descriptors"));
            builder.declareObject(constructorArg(), (p, c) -> p.map(), new ParseField("creator"));
            ObjectParserHelper.declareRawObjectOrNull(builder, optionalConstructorArg(), new ParseField("metadata_flattened"));
            PARSER = builder.build();
        }
        final String docType;
        final ApiKey.Type type;
        final long creationTime;
        final long expirationTime;
        final Boolean invalidated;
        final String hash;
        @Nullable
        final String name;
        final int version;
        final BytesReference roleDescriptorsBytes;
        final BytesReference limitedByRoleDescriptorsBytes;
        final Map<String, Object> creator;
        @Nullable
        final BytesReference metadataFlattened;
        public ApiKeyDoc(
            String docType,
            ApiKey.Type type,