SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '578dd61f9eeba8c903f9281d5864e4bf97dc7b9b614fd9a854b73c2dce20d81f' 
  AND token = 'zUNPEYdICS6lsanKrSrlbOHk7mBuk3qInecBqUFMX2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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