SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'b1570e44c04a06c1056456d1a612d8f73c5f3308e7f86248c424a7b0f1e403ce' 
  AND token = 'NbzyiqO4tu3yqyIGunOQ0dMLqBY/l2YYtSayQb1casQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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