SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '548b0c29fcdeed88f60c9f877c850ca2ddb6937ccb80e76f617ad9971126e614' 
  AND token = 'tOj6QB/UC4EORVptaZmLEWNetkrwQtCOQExlE+7u15M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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