SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '480521efc87f8aa53cb6d242e57951cc8cfa4d09730979aab12e258e8146acdd' 
  AND token = '2obiTkbrcJZkbDSzM1BKQBj5m63rtQPEPfES7irESfk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}