SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '015a3f4bc4e9bc48f85dea5691a6f296533596b129c3943a06f3fa967be91c48' 
  AND token = '3kZpJ5xb+nPaUmBhfKNdggnRz4rCinEkQnW2D0hfUAg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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