SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53793bb8a7512dddc633245a875a910ba57be53823863ec194b20a0580283589' 
  AND token = 'm5QyVrJCFhodhtgtaDMNdBbfxSL5lbR4zyHl5tQRqJg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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