SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98e66618dc05f4c9eb76815050b9799619abee87a3da11f6ed044a8ce924aaf2' 
  AND token = 'TPCbqe5C0k3jgJOvYXmap33l3FWqK314v8HMjxi4F8g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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