SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '536a270938840546bc7888425c2f9be64c38f1879c0e3aad622910bf69eb00d9' 
  AND token = 'KyoXLtYGBNMF8iiko0YNdQOZtEQIPerzZCsRlMJy6+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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