SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd31da36c283694fdea25e8c831ba6a490fd3d5125b93f9a8f311267a25cfbf0' 
  AND token = 'PMFiyuQ+qMcPEeF5/E7GeJcL+KEvfXPszInJInol7BI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}