SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b85957ca22b07841b4a4475aab75436d488e92e13fea09e0c7be4d8ff0620ee' 
  AND token = 'u3/7m/hZAa3UGexvw9Y4K5+3RevjkuLHipMiQB+SxcY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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