SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a7d9bf69d6c8f210205907b7a85e2f334db97a9869e0cddc8379683538613fb8' 
  AND token = 'IsQGhloQudlrYYufVKEuwpXFrz/tGC0dWGo9E5QEB4M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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