SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c618c1cf416f017016ae180449471cd34d7ebb7383b66367483e0f23d3061813' 
  AND token = 'vl9MDlBdPeKpOkizwhhuPB+eYVHsA93550VvpFcrvC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00009

JSON explain

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