SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6961f2bc3d0f74afe3aa49439aefc41e72519d53b899d7296ddc5f93b6d6021a' 
  AND token = '5n08lKtxasxzlMncQZvDx2zwh+dgGvInX8B6PydjvAk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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