Below is an instruction that describes a task. Write a response that appropriately completes the request.

### Instruction:
When has a cause of gas explosion, a Death toll smaller than 63, and a Location of penygraig?

### Inputs:
table_name: table, columns: ['Colliery', 'Location', 'Date', 'Year', 'Death toll', 'cause']

### Response:
SELECT Date FROM table WHERE cause = gas explosion AND Death toll < 63 AND Location = penygraig