SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '908bb1f75f446c0dd529994ae3cfb38a534842ee82e5acb373aef027880f5e81' 
  AND token = '5tGI5S4vgIMpGrJ5jiL+UzrB3QiO1PzkkfWER/NTcFc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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