Distributed Lock with redis (.net)

DistributedLock.cs

public class DistributedLock
        : IAsyncDisposable
    {
        private const string AtomicReleaseScript = @"
    if redis.call(""get"",KEYS[1]) == ARGV[1] then
        return redis.call(""del"",KEYS[1])
    else
        return 0
    end
    ";

        private const CommandFlags Flags = CommandFlags.DemandMaster;
        private readonly string _key;
        private readonly TimeSpan? _expire;
        private readonly IDatabase _redis;
        private readonly string _uniqueLockKey;
        private bool _isLocked;

        public bool IsLocked => _isLocked;

        private DistributedLock(string key, IDatabase redisDatabase, TimeSpan? expire)
        {
            _key = key;
            _expire = expire;
            _redis = redisDatabase;
            _uniqueLockKey = Guid.NewGuid().ToString("N");
        }

        private async ValueTask TryAcquireLock()
        {
            _isLocked = await _redis.StringSetAsync(_key, _uniqueLockKey, _expire, When.NotExists, Flags);
        }

        public static async ValueTask<DistributedLock> AcquireLock(string key, IDatabase redisDatabase, TimeSpan? expire = null)
        {
            var distributedLock = new DistributedLock(key, redisDatabase, expire);
            await distributedLock.TryAcquireLock();
            return distributedLock;
        }

        public async ValueTask Unlock()
        {
            if (!_isLocked)
            {
                return;
            }

            RedisKey[] keys = {_key};
            RedisValue[] values = {_uniqueLockKey};
            await _redis.ScriptEvaluateAsync(AtomicReleaseScript, keys, values);
        }

        public ValueTask DisposeAsync()
        {
            return Unlock();
        }
    }
    
    public static class RedisExtensions
    {
        public static ValueTask<DistributedLock> AcquireLock(this IDatabase redisDatabase, string key, TimeSpan? expire = null)
        {
            return DistributedLock.AcquireLock(key, redisDatabase, expire);
        }
    }