Spatial range queries play a crucial role in spatial information retrieval. Existing Z-order curve based algorithms suffer from accessing a large number of invalid points outside the query region. To address this challenge, we design a simple yet efficient Z-order curve based learned index, ZPI. Building upon ZPI, we propose a novel spatial range query algorithm, ZPI-RQ. ZPI-RQ leverages efficient decomposition mechanism to address the invalid points issue. To avoid decomposing the query region into a large number of overly small blocks, a query region expansion strategy is further introduced to align each query border with a m-order dividing lines. Experimental results show that ZPI-RQ significantly outperforms state-of-the-art algorithms in query efficiency, achieving a 3.6× improvement over traditional Z-order curve-based algorithms while accessing only 1% invalid points.