Keywords as function parameters in clojure?

function-keyword.clj

(defn my-exists1? [lst obj & {:keys [testfn] :or {testfn =}}]
  (when lst
    (if (testfn (first lst) obj)
      lst
      (recur (next lst) obj testfn))))
(my-exists1? '((1 2) (3 4) (5 6)) 3 :testfn #(= (first %1) %2))
=> nil

(defn my-exists2? [lst obj testfn]
  (when lst
    (if (testfn (first lst) obj)
      lst
      (recur (next lst) obj testfn))))
(my-exists2? '((1 2) (3 4) (5 6)) 3 #(= (first %1) %2))
=> ((3 4) (5 6))