SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b2ad263196fb0edc22c2e6051d9815fb42b982aefae490a060acb3dbc6b72be' 
  AND token = 'Kluiy3HxRDAwYU4N9IXMsZceRWlHZef+f6mtX9xQMrM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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