SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e6cb340b7d53d10cef5e728e7f1cb8e824cb3d350a39e0053dd64cdc7bdf4a8a' 
  AND token = 'rbFQnAzqg+vxupxGRYXatBwHLfQWxesO+q8j+Sfdb6c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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