`Are we alone?' The Search for Extra-Terrestrial Intelligence (SETI) aims to answer this profound question. Apart from examining environments in our solar system and detecting biosignatures in exoplanet atmospheres, SETI is another main approach to search for life beyond Earth by detecting technosignatures indicative of extra-terrestrial intelligence (ETI), such as engineering radio signals. Massive efforts have been made by SETI scientists using radio telescopes around the world. Though some candidate signals were detected, none of them has been confirmed as an ETI technosignature so far. Most targeted SETI observations performed in recent years use on-off strategy to distinguish signals transmitted from celestial bodies from radio frequency interference (RFI) generated near the ground. Here we report a SETI campaign employing another SETI observation strategy, multi-beam coincidence matching (MBCM), at the Five-hundred-meter Aperture Spherical radio Telescope (FAST) towards 33 currently discovered planetary systems, searching for narrow band drifting signals at a band of $1.05-1.45$ GHz. Our observations achieve an unprecedented sensitivity with a minimum Equivalent Isotropic Radiated Power (EIRP) of $1.5 \times 10^{9} ~\text{W}$. We process the data of two orthogonal polarization separately, aiming to discriminate instrumental RFI signals. A particular signal at 1140.604 MHz from the observation towards Kepler-438 passes our initial selection criteria. Although we have not yet determined the exact cause of this signal, its polarization characteristic suggests that it is most likely to be attributed to RFI. In spite of this, our work verifies that compared to single-beam on-off strategy, MBCM greatly improves both time efficiency and radio frequency interference (RFI) identification effectiveness of targeted SETI observations.