SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5e1b09b65563e2aec8cce88e16480a920dc8a7a4d13e53669464e2ad23765377' 
  AND token = '2HrxopwwGQk0rBR7CqfYBb2MCRUUw3OeXYk09/A7fKc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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