SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4c5168ab011019774c84ec9ecadfc5fbd0a5ab70941c8609b2dba68e18a0af7' 
  AND token = '7cIpJQv/pl7UUhZ00EKNcKIYSd8Mzy//BYQWiEbU+J4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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