SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1eb851a3e269e69878409fae0977895e48b22a294f3dd2bf99c6501ff88e7db9' 
  AND token = 'xHExt4bwWiLxze6SqcAgv+P0nh6K8iZSmAqE6ovCehw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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