SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '51811a74dfe640d1b43b4774129bea8e608a7a84c10734fd7ad36f41cc6c19ba' 
  AND token = 'jn0igxuCvq4i0MrHf3YLBCQecCxIEJvght6Dvoir9c8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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