SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3bc9b1a1419b1a56bed01309a2788f4796f0ed8dda6691a6a74a2c4799520f9f' 
  AND token = 'fXwke+Qo/QA2EmeUo0XnmvspsBjJBohBYqyCnoh8ngc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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