SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '1f7d4baab034575b134d0a8973db3144819be41a0ce2943e8ce08fe73304c31d' 
  AND token = 'VeXfUzm2BcyB4DIrLNN0Yb3OC6lv9YRLqsKKxyn2UeQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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