SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd68722d8d58d89a198b46c397158319891dd02a3e65da2b6ec92091cb094c0a7' 
  AND token = 'oHUqr0pyh1jpc7T28yPDThFxpLefb2yOmUJqTW8hjZ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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