SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '58b19e391e93fe5caa98eb89b2e620c99c2a59c50ade299f6b9d0325354b0f48' 
  AND token = '8SghuKpgVHSZaTwmVfB2RKNF2zyvS+TfwrfX6CbUY34=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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