SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af37944c0dca2687ad35b17379973cc6b684ac5c2a785f2f64d396a6f84efdf1' 
  AND token = '2rvQv8s9dNNmJE3HKk/V9y0LqXxMDkYPplSwoIoZbbU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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