SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '766ea16a726f789c0acb209fb9faa870a28700ad6e9fa1475c02896cb8986cbf' 
  AND token = '0MTxaofZfo9/gD7LjRLWosA0rN0FhNwnsve4K9j8l0U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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