SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99ce75ecd245b50f76dc994850d358c59f659dafb9ded4fc56a7ab610a3521bf' 
  AND token = 'ewB9BQc5WqARc/QJ3lbcrgy5M7L5rkHuwtdA9Wri8iA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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