SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4c3c954fff4fc96541a4c8c9c584090cd9918394d2ac8e6319bee78c07db994' 
  AND token = 'VECVUqpg66ecpaS+/1/zLJ9r826Da8ObLGSBkgid3Bk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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