Deformed relativistic kinematics, expected to emerge in a flat-spacetime limit of quantum gravity, predicts violation of discrete symmetries at energy scale in the vicinity of the Planck mass. Momentum-dependent deformations of the C, P and T invariance are derived from the k{appa}-deformed Poincare algebra. Deformation of the CPT symmetry leads to a subtle violation of Lorentz symmetry. This entails some small but measurable phenomenological consequences, as corrections to characteristics of time evolution: particle lifetimes or frequency of flavour oscillations in two-particle states at high energy. We argue here that using current experimental precisions on the muon lifetime one can bound the deformation parameter k{appa} > 10^14 GeV at LHC energy and move this limit even to 10^16 GeV at Future Circular Collider, planned at CERN. Weaker limits on deformation can be also obtained from interference of neutral mesons. In case of B0s from {Upsilon} decay it amounts to k{appa} > 10^8 GeV at confidence level 99%.