SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '778a9750f247f8645a17cd559e1ef03b18e290b8e77301f3b304afe62f132394' 
  AND token = 'quEKTGAO8hvhOzK7wnhc3/XhonwN5sB6TxW+AvYnuqk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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