SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ec8985260e0c84eb1a6344ddda2c5f667a72c4b970111ba36067598ba997eb7b' 
  AND token = 'u/b1QNpOzlEXnYba0S1eLFbkbr77yPKg2cSa+QQs5Bg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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