SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a3d156ac46d96535a2ebc406485b40e266b8c09d1a563c4414463f822368c945' 
  AND token = 'XprLR+O6ZdGQrYtQ8xJexT0cwJz6atgt3RekaCMUZ1k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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