SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'f6cd1913cce9a0200bcaa37149332bfe7fe045413f93c849b70324bc05d03e72' 
  AND token = 'xl4moozsIzTm+PoTMHfkyys9k7ZiEbqBdZYBSxDWxoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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