SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'fc5c75690da9686637ede00773124f1a246913aff2a618c6b19024a564c06138' 
  AND token = 'orTX5Gnl3TjDmNVGx0vPzadJ9CGHzbtiY3vKxrv6gDw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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