SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2d9a4d750d752db01463f4b93725627766a20398ed0f9f8eba57c36c7f6e5b79' 
  AND token = 'WMJ+AKp0waz3VcggqnvoM0AlblGNjH9ckwzR1k7NpZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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