SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '29b01fa0da3a41800f36effbfca4a702489340d4996ea0d12937bdd4f13424ef' 
  AND token = 'YbQtRU0CawNCBU7AqjzhpSwNfWvTiga9ZFQ+tvbDIz4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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