Picking/Selecting in an association

Query[Keys[t1]]@t2

<|"a" -> x, "b" -> x^4, "c" -> x^6, "d" -> x^9|>

t2[[Keys @ t1]]

<|"a" -> x, "b" -> x^4, "c" -> x^6, "d" -> x^9|>

KeySelect[t2, AssociationThread[Keys[t1] -> True]] (* or *)
KeySelect[t2, MemberQ[Keys[t1], #] &]

<|"a" -> x, "b" -> x^4, "c" -> x^6, "d" -> x^9|>

KeyIntersection[{t1, t2}][[2]]

<|"a" -> x, "b" -> x^4, "c" -> x^6, "d" -> x^9|>

or

KeyTake[t2, Keys[t1]]

<|"a" -> x, "b" -> x^4, "c" -> x^6, "d" -> x^9|>