SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28c880137b1f508239a94b5fd36d1822050c0c27f77082545aeb536b39fdfff2' 
  AND token = 'N6LuZ4d60UyMY7oXCQRLHwVT4xg57VFHYtjnZAbPNMM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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