SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2b475ee4a6f721cfabdd3b40251426353fa0f1e10b3b284c1f31b58298cb3c78' 
  AND token = 'lP3W+KADX9HtckXmnXFhCxzOqcywrxxEhesQ+LWFwAQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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