SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '424823c15bae76740a50c78209e4ffe4817346661cd33e4c386530ab1bec4ad3' 
  AND token = '6AGUOnLtKlW41m5uI92zr++yHKgtTOaIHcTq8TxxweI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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