SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c69f2dcee56efe0d294f22a93b17e139acb8f0900f8eda57ac4e2f4fdbe9c83b' 
  AND token = 'FBmC/N5ZOewZzQjK3YfnjrJ8lnFxWtyDMDQrsIgP7oA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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