SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd7ed7f6cde6eff26204fc2d4669d80828135dae6c21905a96d8287497bc3cd4' 
  AND token = 'np1uwsFDKvVpTjvuf97S5uFaYOFljzHOD7sD568ycQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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