SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1908851ba1755f1c7b34aaa331574ba3261a1a232ba90595a97de76a94877942' 
  AND token = 'pju/WAof3+Fjt5/DC+PsCw3vm0oPBdo6V8hUYHRLIuU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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