SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e0208305775a97de65c67b08e2b628dba2f4df67ac006de1e7df2684c6869cf' 
  AND token = 'EmrUMVeXrhJtMkGziez9mW7z+OURVhZgJSITxpjNmvY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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