SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '08da98cacb966bd202e5c12d221478d45cb6fc222e368bc16bc0d88339d73bb7' 
  AND token = '/rq5CudGYoTfyncWYWLZkwp6YWOKhZwJYQMWenFnGu8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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