Use the --timeout flag to change the timeout.
herbie shell --seed 2020322
(FPCore (F B x)
:name "VandenBroeck and Keller, Equation (23)"
:precision binary64
(+ (- (* x (/ 1.0 (tan B)))) (* (/ F (sin B)) (pow (+ (+ (* F F) 2.0) (* 2.0 x)) (- (/ 1.0 2.0))))))