SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad028878d896a8c532ef750a38ace08135d4ad4e927b2fb3015a6984eb18ea99' 
  AND token = 'Ow3rqAstXcCcMbpS9ZXRAnKWhqxm62whUlrgAuWHFBg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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