SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '9b5ab4fca73249017b80c017a4b9f5656e54328cff93d08de7c65402b7825fc2' 
  AND token = 'w4cVcbMNVCHQZLCTabX++s1Ayr/RXcK9Z+UxgfGEz0I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}