SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6d23b5cb73d46253d006ffda7628e14208f2a42e2352fbb3ef70f51f95201c5' 
  AND token = 'vzr3lOKxaHYSLLFxnbYhXQK8fLzxYZgUNq/03q7Vm4w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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