SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2603eb7fec406273aed35a99423401ff60328008ece8c206d445a40b86c4f8ab' 
  AND token = 'VQWUkVMBDiH4ZfwKZx477IPoGvZVcGMqEVYhhCWYRfA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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