SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '857216a759f31403dcdcb0fa569222e038b861cd7e8c28dbefc2e4f8af17ebf5' 
  AND token = 'PtpOvI8gOk7ZERsTQOZ8f7xUnRuK7+JhTvC/Wrl9CV4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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