SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b5e024625d014d62c33f09dc0e2d81c8ac85473640c4380a242470f9f794ade' 
  AND token = 'gMMnWsXRCsvG055Vxz/qy3kK4aBW1doCq3A8rVH5AwU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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