SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a36aca4eada77604a8d57506a5276bed3a83657a1f885127c9fc753ae04fbc23' 
  AND token = 'uKVADPhSe5+U/cjiMTSyjTXMWCEC2enBsfgDpO9Rtws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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