SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '839fe6b6ac62081810d9aed1020fe69fd132f5626e9527e1d8d0546f91ba3ebd' 
  AND token = 'csVgyKLaQ6JDblvo8uAsumcSb4gAIPRoLxJtJXN6qq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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