SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '24c249d9f741686be9bcd34b5bdff9703406eda388bb663fc092996508188a8b' 
  AND token = 'UR3BlwgdF+b4oY3cmRMOdUZlgt7dJ6tXcIpUgoHvuVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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