SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5b66f7f325c5428f046f81f12dfdf7a432bd7987e228b35bef51a4c6f1537f7' 
  AND token = 'UZZVhv9QxW5gGkyGcx6X8bxUp4QuXotOrLonqwcPb9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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