SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd8448536eebcfb8eaffa4d289c96894296d514b2cea5903e0e24e43adcc87ab' 
  AND token = 'WIb0YBRJixgbu2Gq0ZTxxUsQ1wtjhxGUjsqBgvnDTH0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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