SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '858b731ee6faf8fcf89d25fef52555d517e5d493e46f5f1befc506b2ea3c5fca' 
  AND token = 'hQwyEP7DMm5TPdZICCvXOh2TuBT7FMu2TtrsMDZxqm4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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