SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81c6153d30e1fafcbe825d869d50e0dc93e19d46f378fdd6a220dcc75dd3ab0f' 
  AND token = 'rMzxZ6pLjUQODHl5uFLGOFqBMBYiOtTvOo0CHZ4eioQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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