SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ca9990a4297cee111624454d73e0fc7295b197258926e0dc43a95898b2ea24f7' 
  AND token = 'dOatPj10nPYXa3qMRj6nNKxiEbD+HV3jyeIWIE3QjPQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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