SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f667b3ac8361e5f44d4d6768b9b453d0ddb64e5020da413ed3675432b928976' 
  AND token = '3heFq8tOLDRIpZNv1ztVgCZqAEjD0WwYAKrzpn5Mo/4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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