SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '32909a28b8f949acf0e862ae3098bb60c587854e2231be64b3f5f39101f32538' 
  AND token = '0KfUh2lxmDiMgtVWk/+zKOxy0Pfdv3ZGbCQinnxXrjg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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