SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7b4bcd4fe62e9921815c7d0a491cb2497a9a14866557155fbc7eb62ec92355c5' 
  AND token = 'Sbu8+uceOQAcO6zZY+Rwv2AIfQNGgT1GiuH1MV46BVI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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