SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '18f736d89c10146a499bad7f1cafd3ab85f814faf629714b3f2b87f0d7aae11b' 
  AND token = 'R+Xm/kYNeQkdRBBwMPKPxHdCynYb1aKKsNKBnTuVxq0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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