It’s hard to know when Blackhawks defenseman Duncan Keith is kidding. Keith has such a dry sense of humor and such a deadpan delivery that it’s hard to know when he’s serious, when he’s sarcastic, when he’s angry and when he’s just messing with you. Teammates, staffers and reporters alike have found themselves at one point or another just staring blankly at him, waiting for some kind of confirmation that he’s joking. So when he was asked about his heavy ice time at age 34, Keith looked a reporter right in the eyes and said, ‘‘I want to play till I’m 45.’’ And when he recognized the familiar blank stare, he quickly added, ‘‘Honestly.’’ ‘‘Eleven more years,’’ he said. ‘‘I feel like I’m 22 right now; I do. I’m 34, and I feel great. I feel better than I did at times when I was 27, 28.’’