SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c288cdc3adb3490f1635f8411436788ae3be16994e501ebd6afa886497dc9a72' 
  AND token = 'H2WGOVmtj9FOdbeR97D6NkimrjI3reIx+/3U4hFuywI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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