search-some

(defn find-map-with-key-some [targetCollection targetKey targetValue]
    (some
      #(when (and (map? %) (contains? % targetKey) (= (get targetValue targetKey) targetValue)) %)
      targetCollection))

(let [ex1 {:key1 "a" :key2 "b" :key3 {:underKey1 "a2" :underKey2 "b2"}}]
  (find-map-with-key-some ex1 :underKey1 "a2"))