SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e0681572091448f58d63d5cbabe87553e8536cd023726e39669b3dd177c0583' 
  AND token = 'W0Zfj1hRueq568tkM269HGncLTN4ra3bwcSynwUQq+4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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