SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ac976de6cc0ccb56180ae314a2fbf7587bb2526e9d5e664f0a4576d61c788111' 
  AND token = 'i6jDzXo2QLAC0DgZlHEOTzbEX6Kd1L/rQF8wTcDAS9Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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