SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c24fbda6c1ef8c1322ac14e578b281478fe2ed4bb9bd9f78cd5ba6eb4c47255f' 
  AND token = 'lbq4/JnWnW8BgY4+wj+IjLquB/PMJd3GJHMbF3ZfaLI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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