SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8f86cff86139b9b6104a18e1fc0d5ececcf53dbea8aebf7645fb664e7171fc71' 
  AND token = '2ZrUmqtzI/vAJKtV6CxyJz54nCLf/ldRUzx0gVBw1jo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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