My question is what is the algorithm that a miner picks a transaction from the mempool to include it to a block?
Miners prioritize transactions based on their fee rate. The more fee rate you use for your transaction, the faster it can be included in the blockchain.
@OP, if you are in a hurry to make a transaction, increasing the fee rate will ensure that you are given priority and you will not have to wait so much. In the mempool every transaction has a priority depending on the fee used if you check, there is a low priority fee for people not in a hurry, medium priority and high priority depending on how quickly you want your transaction. Miners respond to a transaction depending on the fee.