SET @index_exists = (
    SELECT COUNT(1)
    FROM information_schema.STATISTICS
    WHERE TABLE_SCHEMA = DATABASE()
      AND TABLE_NAME = 'traffic_log'
      AND INDEX_NAME = 'idx_timestamp'
);

SET @sql = IF(@index_exists = 0,
    'CREATE INDEX idx_timestamp ON traffic_log (timestamp)',
    'SELECT ''Index already exists'' AS message');

PREPARE stmt FROM @sql;
EXECUTE stmt;
DEALLOCATE PREPARE stmt;