SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd4cd5043d544233390f023caf45befbbc9cb38304633201bf39e5fef21df60ce' 
  AND token = 'lZshbrCjIpEwpbPCBEec3Oc7IkndpZ/tG8iwuumh1PI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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