Lock cylinder suitable for actuating a lock bolt and comprising: - a cylinder housing; - a driving pin (5A, 5B) rotatably housed in the cylinder housing and wherein a key seat is obtained, which is suitable for receiving a key when said key is introduced along an insertion direction, a predetermined unlocking combination being reproduced on said key; and wherein: a) the lock cylinder is provided with a logic circuit which in turn comprises: - a reading sensor (170A, 170B) suitable for detecting progressively, through exchange of electrical and/or magnetic and/or optical signals, the predetermined unlocking combination reproduced on the key when the latter is being inserted in the lock cylinder; - a logic unit programmed or anyway arranged for stimulating and receiving the signals from the reading sensor (170A, 170B), for verifying, on their basis, whether the predetermined unlocking combination corresponds to a predetermined opening combination stored in the logic unit and, in the affirmative case, for allowing the driving pin (5A, 5B) to actuate the bolt by the driving pin (5A, 5B) rotating on itself with respect to the cylinder housing; - an activation switch; characterized in that: the cylinder housing comprises a keyhole, through which said key can be introduced into said key seat and b) the activation switch is arranged for: - activating the logic unit and the logic unit activating the reading sensor (170A, 170B) when the key is 0-30 mm from the lock cylinder, or starts to enter into the keyhole by making the logic unit pass from a first null or reduced energetic consumption operating mode to a second higher energetic consumption operating mode, wherein the reading sensor (170A, 170B) is housed in the cylinder housing and is integral with the latter, and the reading sensor (170A, 170B) is located between said keyhole and said driving pin (5A, 5B) along said insertion direction. - a cylinder housing; - a driving pin (5A, 5B) rotatably housed in the cylinder housing and wherein a key seat is obtained, which is suitable for receiving a key when said key is introduced along an insertion direction, a predetermined unlocking combination being reproduced on said key; a) the lock cylinder is provided with a logic circuit which in turn comprises: - a reading sensor (170A, 170B) suitable for detecting progressively, through exchange of electrical and/or magnetic and/or optical signals, the predetermined unlocking combination reproduced on the key when the latter is being inserted in the lock cylinder; - a logic unit programmed or anyway arranged for stimulating and receiving the signals from the reading sensor (170A, 170B), for verifying, on their basis, whether the predetermined unlocking combination corresponds to a predetermined opening combination stored in the logic unit and, in the affirmative case, for allowing the driving pin (5A, 5B) to actuate the bolt by the driving pin (5A, 5B) rotating on itself with respect to the cylinder housing; - an activation switch; characterized in that: the cylinder housing comprises a keyhole, through which said key can be introduced into said key seat and - a reading sensor (170A, 170B) suitable for detecting progressively, through exchange of electrical and/or magnetic and/or optical signals, the predetermined unlocking combination reproduced on the key when the latter is being inserted in the lock cylinder; - a logic unit programmed or anyway arranged for stimulating and receiving the signals from the reading sensor (170A, 170B), for verifying, on their basis, whether the predetermined unlocking combination corresponds to a predetermined opening combination stored in the logic unit and, in the affirmative case, for allowing the driving pin (5A, 5B) to actuate the bolt by the driving pin (5A, 5B) rotating on itself with respect to the cylinder housing; - an activation switch; b) the activation switch is arranged for: - activating the logic unit and the logic unit activating the reading sensor (170A, 170B) when the key is 0-30 mm from the lock cylinder, or starts to enter into the keyhole by making the logic unit pass from a first null or reduced energetic consumption operating mode to a second higher energetic consumption operating mode, wherein - activating the logic unit and the logic unit activating the reading sensor (170A, 170B) when the key is 0-30 mm from the lock cylinder, or starts to enter into the keyhole by making the logic unit pass from a first null or reduced energetic consumption operating mode to a second higher energetic consumption operating mode, wherein