SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a61d8b670ad08fcf45d728812daa3fb179662dccd7deeb0d251cc3e873f135a' 
  AND token = 'ZbhAUJ8T6O8ZMWd2qhF8LQsvS1wvkDui9XjXhFhIbPw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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