SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'afc8820cbafab133909d92bcb6d952cb459eacd8719fc2e8aca51daee4f7df80' 
  AND token = 'ajj2gVEGGtjyRy9HN01kKEzhp6zmcgH8vf6UYBqUd5s=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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