SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af8e3c629e9c91572fc5978cdb33bf54873b9594ed3558258d6773629dab82b9' 
  AND token = 'rVrd7FWLWXIu63MZ1O0dIyG9DEYBZ6BRf/6aC8iAMwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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