SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68350c22c0f9797ab571d635c4874ce3d25631beccb02f3091740b461a248bfe' 
  AND token = 'S5N+v63QsZD0KCg0smXTbdGRdCkjJr94Hy5vABamn8Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00121

JSON explain

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