SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'ddf552b0dffd8485606bdcf8b55c926c69f82676fee937cb22b0bd86dd8cc175' 
  AND token = 'FXBbI1a9b9n51ELykFMIiuWovAvbdYhucWpmANs25BU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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