SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a18b82d3a79b5b6dc8926330c6093aa0ef4182eff24c904fb3f229694afcb5c' 
  AND token = 'ILC//cJpmfc516h0cGOYFQCuXATUhnfphzQBS4KVPw8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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