SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8dee1a5bb9861a49bde6654a3bb956ee8dcc9652e521b3fd411cecef422bd46' 
  AND token = 'bSR0d1nMuN1bPaSVIYRIKqM1GllGCNVvKzC6mLD8YzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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