SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc588459ecffac1dc17e987bf1bad4dd36340413db1e0596d72fc6f6fe24b9d9' 
  AND token = 'UxHFk+ucrYTFrtrKurLAY0amCNWGXhCqdjYrqgzSgEw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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