SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c186f133055bbfcd62ad3d57cc2edf24e4836377474fa25e6b1fe74f057a0ee' 
  AND token = 'QpYJc/WoPjnsxj8n+gVHw8S/F8A+MqMrL8qjaCSwWhQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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