SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53c00685f82b808730a97a5403dd872a0dc52e22b83d28c0f13fdc287abebf20' 
  AND token = 'zSdZ+mwJ3IfGVyovYinC8vt5pkSrP9MkGBncnW29Im0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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