SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18300a76535f47c3ab5747855a8c656de2ee814bb9da6d1b8223913a92871af4' 
  AND token = 'h9YoP/55K2qwV2J4lT489ItCEQNm/VXJS+obU4BWbo0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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