SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ae40bc44919ea304e493ce79d44a54d4b34c68a889193191b186897a99a4a79' 
  AND token = '8P7xAzqOeOgKRanNE8kHmS+5WnfJsxcwqvy5Ys0S4i4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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