SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cef8fe973c37e4ee623c99bd169e3858065245f710b655436ec15f2253b46af9' 
  AND token = 'Tznq1At6e0XmL2/VSyqG1Tdj9ntvXwHX8EIdcVNI/Fc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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