SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f1eab1ca15a36d931a68dcc1a6ac2aeaa83c8bab086967126fb3cc47c6e3604d' 
  AND token = 'JJQ7A/6OwSp7SsVjj8CVr6RfisLjFRYcSSoQyhWjwz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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