SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52b5b7d7940e5ca1ef0baf4f96aeba53fc088302e72da3f0e58a908d152defd0' 
  AND token = 'AiOBixFD+KoiNnNGSl44aGk7eu43aUiVfK+wYUwQSf0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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