SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '83a6cf53e9efdb74fbee88952b35b1998a7fbc9c988954ae3d0cb3202456c1de' 
  AND token = 'MZNItfAxmEb5LayE8g9ETMFwXR2A0+BbqILPDzxEwQQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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