SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '57f28aab63e881708f0846684d533a305e439afd0aff654179517ef1a61b5d95' 
  AND token = 'kGIILq2iuEdhetewFIq4zt4hVuMyMaNSd5sp3vTX9RY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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