SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '727f9b400195150dd744998156a80b3b642e4ec5c0478a7b1c6255f714dc46a2' 
  AND token = 'MxWbLzzhxJOHBpqIzxDIejA85vZqvV1+uc2FHkyE1bY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00050

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}