SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96c3c18038f5deb08da2733e56dfccc902747992b1fe566419da1c2b1b5b6c45' 
  AND token = '3ZDqVmLk36/Dm2viPDpTYdsECUujDgqu3n13+HdKwjI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00072

JSON explain

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