SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '86372421fa1970c8fd3e1ace86a66044c1d24c6d2b2616488accedaff2f09df1' 
  AND token = 'oaZ35S2I8W7fe+k+qS6lh+Y8c5D+Jj/v8+YORqQ9pJQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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