Efficient way to find if map contains any of the keys from a list/iterable

I need to check if a map contains any of the keys from a list, and if it does then return the first matching value. The naive approach that comes to mind is to do it in two nested loops:

Map<String, String> fields = new HashMap<String, String>();
fields.put("a", "value a");
fields.put("z", "value z");
String[] candidates = "a|b|c|d".split("|");
for (String key : fields.keySet()){
    for (String candidate : candidates) {
        if (key.equals(candidate)){
            return fields.get(key);
        }
    }
}

Is there a nicer and more efficient way, possibly one relying on the Java standard library?