SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '293ac7b79813ed8e946551d6dcb317e7ebbe200772ba2bb7df9e36bf14687ca6' 
  AND token = '8JEYCS5vCdlQKlDhr+aJ70y4ZQvgIZ+H9UDPuGszqCY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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