SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6978f0c3cb1a6f04f0ea2017e076d2df6da220ced748c03333f4cee77b33bdc9' 
  AND token = 'tudbToaJswwuZKLKDQenGNWD9c5KppfCvoaeR/8alYU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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