SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '996aa80397a53caaa31e9c66a2727d90d12e5a92cc8bcd73c8d3580264bd82bb' 
  AND token = '0+bG0k41Cvr1HFSynaxL86aO+vAYrcuwBxJgXOmtxm8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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