SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9be95f4de079c9149b5af020d142fd849475b6c230dc1968d3d76dd650950c4f' 
  AND token = '6tr/EeV5NC2w5mYRPivqFNy/kVP7nwMLfbCjHGYBPhE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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