SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '802577c237dee91e7fc80940de953b43a9f6a325cafbddb6f7b590d66902b977' 
  AND token = 'htho3x/mRu5iUaMqs+dR+zpgYLE9KjUPriyOpHGy5g8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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