SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d7e24e38193f481995c82e8505e4a0ba61af21bab259ee23e827a7f41313de6' 
  AND token = 'j2sGMhP07FWrDWL8OO0lbhOGVI0ledCWBjzcYQq1YXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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