SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e9232721fddcd327b2371483a35b4b91c277a5c9a3c7efd27e0f8e2e104e1c8' 
  AND token = 'DuSHsMeJZdkiGbWXW8zdvWqJKS9cEl0CmjOlgwNI980=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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