SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cc995afc4a985947359bf85aadf24f56fa6822f618854907fb00c786d1b5aa3' 
  AND token = 'dbnykUPvLSlQTwY9ebd1Gr2fWVDaWMRoOEVLIkrhaUI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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