SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '358dd5b53f4f37f3667beeb38a4397988e5b523a6f83e31b36921c47c3391a17' 
  AND token = 'gXwz32egmwaWvLfY0gGMVg/oweTYAFgFVqUc8BauCxc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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