SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '667782dd68ccb9751378f14dd336e5a1c4d63815685837f907a8e5542d7bab2b' 
  AND token = 'YnOtlvMoXEEkGAVfOjUeTEHePdUzUMSCIlzoGuO7aj4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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