SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6a1cb4fc88e945d88d797eb416087389a28f7c0b24d2fa330553e3485ce61932' 
  AND token = 'W3/cuVnO6QwsQjKfns1veT/448O2zlTYw1rmCZSwbgU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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