SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '734d3f60f3104e09765ab1981704ff9c68c470eac36e9be43a2329694f118da1' 
  AND token = 'tO/UyhYlN0g6J7AV55GbCan+er/Hv+PB25lsq4y3VBk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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