SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8fc3831c5763934722e24de69fc215bc4805dbbc4f97f2ca37ea239a36f3a354' 
  AND token = 'GPP2MqI9yhp2vuDR+pgGQPfoUp3ZzKsM67BaIOST5Z4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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