SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb1ad75287f8e0b038059e4cad92583782ea0740c59dee6910900f1cb4069573' 
  AND token = 'PsXK4FXOkfdA6qQxO7A07z7pkNj5T4QjFPHLVJxFz2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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