SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cacf6fe473a9f625e032b415cd026f35072391e45b88861bf7e7209b188eac90' 
  AND token = 'asnGfMuczVuFQ9jvjV7B2wHqE7WiJqey1luGKlyxFEA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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