SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '250d98ef4b8b4a155526e0fe5f7b5beaafcda1af96a242d6db99a90606a63c22' 
  AND token = '1FLrP9L0XCWZbxAqQBmQYpCkkoFk57Y6c7fAURkuE8M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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