SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9c1b70920b67b189122ebf08f3c5d85c4532a34fb0c83b6a2444f22c66f8e958' 
  AND token = 'fTVvjMSYBUi5KVRsNVHZybkz2tSBehvT2QtIDuzJ7iQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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