SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3946063a92de28f4b69a65836d8c6b2ba0191ad9838fc6d877bd0c829e698ec5' 
  AND token = 'lYmQoQgiS/AhB/vUdIP9hnUJrsWZ9LVflmjpMOH0rYc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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