SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cf971fd4e14743071ebd56162f74fe3438c3c38fb17e4a8475c32cfa3da5f786' 
  AND token = '/mIaM1i56UEnkIq0NZqJFYhdoRAGsyg59L+Plgzzt6U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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