SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b70a1710a8185ddd39a7cbbf63c9f10fa23b95fe3c4efd632cbadc841bbe053' 
  AND token = 'SmbhaUTJv3gD1Vj9PDhkXuyiveRLnw7NhPKrvDXZa8A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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