SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c636aa893b9f9c94897e30466ba183af3d967695b4861b33373e2c5ab7f76545' 
  AND token = 'cAccpJfbUd/sHvDSs6TCbslGO+WeL3xGIPCuJQgime8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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