SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23826202a3b1d870337674008a819d8d21cc8b37d50e76209585319fed5feae0' 
  AND token = 'z7OcxPqzBIKn8xxbvf4+b6mXU+HUNAfUeWCgSUrQo6c=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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