SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c25dc94b9697d36802035ba9984f93fda47635c253f402a3b40ef6b3fefa3d15' 
  AND token = 'g4TzFggPAQmvyAGJxnjqoLBwWksQcn636igZdyFd5Vg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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