SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e0627a53342fb185d298f51235e80baf6d72d7f4cd59cfaa7967f8bfa013fd4' 
  AND token = 'Th5Xwp18ng+Tw1CI/YvFf/AYz+Os4p+GIrNYbXN+CFY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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