SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd5f017dddaa685659feddb9c393f30229c12691b40d9ef4cc2e7e58454d2734b' 
  AND token = 'a6kwhmTRf6R0ZOJ3ppdYMrbDXsuFF8dVBgKFNGeO8W4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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