SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'd4a1783cb09733ffd74dc722e230879f56f624de15e399b756d0016728bc7b9d' 
  AND token = 'BA1jSj6aAj9Qvrru+PYaEYi+8qWi2BeHmomxslnGxh4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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