SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '41539226052829db251d78956d5b48f6ff6c7e938d54b53e955fc258e439599b' 
  AND token = 'rcAyW90gHXyfibuNAQTGGApTSwDU2W8vUBkRbh1HhuY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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