CREATE TABLE IF NOT EXISTS `user_fcm_tokens` (
    `id`         INT UNSIGNED NOT NULL AUTO_INCREMENT,
    `user_id`    INT UNSIGNED NOT NULL,
    `token`      VARCHAR(255) NOT NULL,
    `created_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP,
    `updated_at` DATETIME NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP,
    PRIMARY KEY (`id`),
    UNIQUE KEY `idx_user_token` (`user_id`, `token`),
    KEY `idx_user_id` (`user_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;