SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3dfdf3191c281d21a061469a0d61be870b5e216a3bef11cdc9f236b3a15a0ee7' 
  AND token = 'KoNc88lHukIovJEZBC4VcbyWgOLiumZlsOM7+8kbgGs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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