SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e2070334b233772ed9a53607a2fb40ccf1dbf0fc9e351026a376c995449691b9' 
  AND token = 'g847sz9KG4k6s1suM4ozYOep55wUCWfVCddxNDZATuo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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