SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e906d91b7d097a80457372cdaeea5e1433fc1a9b1c46ba8d29fffda442e74fd3' 
  AND token = '69dHup0Lq0iQ/4HZ+Km8boMMIujQrswY1xRncTQHGQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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