SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4bf51c308adf8f4c6b552b665682037692bc597e63e22dda172d2bc76f31c889' 
  AND token = 'PZy+uZrmnERugeEWVpdqhMt5nUTNv+XkCBNpjy8v12E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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