SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac38fb7d9b4f944f14b71c6d47e2b23e59f2c9bb17b8acdef24562d63655f994' 
  AND token = 'xKqEs+nYHlQdsAIx5YW2pnw/7tzil86vDuxjpGcO+xM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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