SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b707777151eb600b16c67125286cf0c963a412646f9a0940b46ddfa00008129' 
  AND token = 'pq5QIOcxD9X9hhqcOKSI1neNThJbOZi4pMINR+J1xNk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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