SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53bdd8a5a0c205622057037c49ef6789105a13b091d9c343248e01baffd23704' 
  AND token = 'nX+AwgRhKKhpTqwp0eBM2zeUF3HzGWILLckDlE6XCuE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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