SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f742e8812510a86a71e8194faf072f32b2080f8fb09f822815aaed2313efe1e' 
  AND token = 'MnJ0NTAvUrYQfDC+HhcXucSfACJ4ajBTCZf0N1HzfDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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