SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f68f8a23d3d55636bfce926b98c5f93186f89041b92617818f2ddef765920644' 
  AND token = 'mTgIl9oywsa6UgbirQj92NktbB/nV8Wq4NQnCpXCG4U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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