SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ce3435d913e63a693665bacf130f2c3d8c47a9f035e29874fbbceaaa94719c47' 
  AND token = '7KVEH/QVwZj7q0ZliNe38qhtlbmwV/ELTF+h9uD9XR0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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