SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b91004cef604e838459b720c9571745e154a07c72f2483fca7c08c331161b40' 
  AND token = 'J2ONatqtx+oAFeKFhSBvqXfoHWfF6bLlIxHTQPvSwhY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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