SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00a9831868825b7ef340793e2ba8852afe24cedb180eb2758c75aca49239d262' 
  AND token = 'b8hBhPeXgGud5sxCzv/LqUMH75qyGvuLBDtW7CLqsNw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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