SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50c5c689fde6ddc87311ccdb1cf214ba84133b95723c8eec903cf316af8b3992' 
  AND token = 'UpXEiMq0B4J12TcKRojvmxENEjyu53Ec3NqEgdCbG2g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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