SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f259958a85d63f7c125416937a67520a1fec7b7915ddff328f1b6f455d4a439c' 
  AND token = 'dHTLA9H51/3LBVdADFhEUt1Gtq4ImhnSrmHr7VJm6ZA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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