SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3ccceeaa4a007066e008c0d7505753ed1712c8b312460441339fbbbd260b5b0c' 
  AND token = 'gCWrTUwZf02LzmY8vgNTlHKVHQVTzlo2GnyKPl5Ao54=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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