SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e42575b912a2350c538faae74d3d27dd38cdb559d751d07c0ebdcf35351024ae' 
  AND token = 'GYirMNezd8str8wAz08JHEeLXmlHZVtWeusYl0gvdSU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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