SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a5724b36d050843bf1644ec2e71469935886d4a71c3d03b8e8fba6f9a3aa6026' 
  AND token = 'NlmRwTVTDj0mdAcQTVRdCPLnKRFhAvcB0MQJip6kk+8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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