SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99bd691a1aff36d1b5891a78a46f91f889c163f5d7c49b4ffab2fde1d8685808' 
  AND token = 'JtPs/+YOsDCsAyLJsp9pedcvbY2GJcvNWCghwu1wHwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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