SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '918b87b09876e72993f37e8f503eea466f6c490b4c396e37055c59c0ea5cf608' 
  AND token = '8HJTGBaOjCYz1zqCQlOIh8IMmWl5VF4q8pDGHsrvkvg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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