SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fefb1a0fd6dadbc446296639acd921c10beaa814f7cc0b5e067d7caa1180d5fe' 
  AND token = 'wJ6EEOo7DyOQypy5jzHtXUKCEqbj/INwXObCpc7Y/Tc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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