SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '841257e5dc912a6a5c8e29593f365184b7fae3bff92f29a78fd59364a8caf2e7' 
  AND token = 'PfK7PZypBXiJhrzHW0DVbQuXG9bZiT4Yzs6uvViB/2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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