SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '15e3dd9356e0bd73266c734f6439f51c44145b108553616a929c63d578200a5e' 
  AND token = '7CHlE4KFuIZIwDBkBkh+jWvXEKyjF7il/3n0n7Kg2pA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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