SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '25c9db8efa31bd2819bb558fb5729167c8ce54ec3df55845e0666357deca2da0' 
  AND token = 'eXEwB7HEQKGXKDSQBM/QhzB4t7WF5QnFqeno2yOAAoA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}