SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '51ca2e37eab7f6db56ad26ecf74fb728d2171b40b0ea74891b4c6e5b99e99bc7' 
  AND token = 'ZfrSAuisD+JGpAZQyEg2K4CKhORgBVBhLepCUG6Gj7c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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