SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16cebacbddf180f521edfb081da5e3c1871f48ff1514a9c0e30edb259a0d69f8' 
  AND token = 'u0u9Onwe0QjXCJf2MXYOooTP+68WtqCsDMMkvo+gfNg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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