SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '574759c17e04f9259e08ae7c68fae9868aa9ca2624fff0d0a5016e4de49cc17e' 
  AND token = '319m5rBnv0lDKoCuxWOT2eozAHVMlW3zxkhykUG6qo0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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