SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b3ae9a3463f0a10aeaa742b66015c025911a5e502af36065b3acc4d4359df85f' 
  AND token = 'WteLXpAkPSsRqkmHMJOae/XyIpaaEGCQchD22KFWpHg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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