SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c440e5c49e5fe7deb21c5761701359ffc7859e849b63aa84c8b46a3d75ba9e8e' 
  AND token = 'tZpzpxFv6VLYK5KG+m59uCEXI+VnJJ+fyh0HBtHcg5Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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