SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '98353bda91410186ffadb1e6898dfd8e63bf7ae23d7e4d27946a7b338e712c0c' 
  AND token = 'SLLB3BfcQ0DZOqE4yeMUdlbYlbsf8cj2zsd39crxqXs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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