SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87f82b12efb80cbf63143eb3e9d2bb314cbd246a6a1642ab9a43547929b56d80' 
  AND token = 'vrHH1JZaaqWjzFvw6XCqXa3pElp3yqaxsqj+I4gNVKU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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