SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '37c5d517c56db0071c160136dc66d312eaf452c5f79cbf97b21f056361400883' 
  AND token = 'vgkMuXI5Hrz2wPFWuC6YgIlxZN8bURZfp+F4rCl0xUA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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