SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7d351afb1b8c7e89f182c2b0cd3f84ff3cfc01c05801ce641ae5651c815cbd8' 
  AND token = 'GWALmKU5+NGmg7+gjiyDiAsojXwzXcWhVTxbgMwZuHY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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