SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '03c45578ce3bb4adb82cbb711e88036b00728da012f39a861d498493946bad4e' 
  AND token = 'yCnLFeTbJpwc9040pIQ3xgcjTZTRAhIf+xoWvQRVcKE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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