SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f068051d15b4604774d0440ae09206eb923de71443284f158331dbdd677be03' 
  AND token = 'fWvkveFJtlD4Ze7mv3smJRFXSvUEU6zuP3dwqh874hA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}