© 2019 CERN. for the LHCb Collaboration. Published by the American Physical Society under the terms of the "https://creativecommons.org/licenses/by/4.0/" Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI. Funded by SCOAP 3 . A search for the lepton-flavor violating decays B+→K+μ±eâ" is performed using a sample of proton-proton collision data, collected with the LHCb experiment at center-of-mass energies of 7 and 8 TeV and corresponding to an integrated luminosity of 3 fb-1. No significant signal is observed, and upper limits on the branching fractions are set as B(B+→K+μ-e+)<7.0(9.5)×10-9 and B(B+→K+μ+e-)<6.4(8.8)×10-9 at 90% (95)% confidence level. The results improve the current best limits on these decays by more than one order of magnitude.