SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81b5c6d6fecfaf349968ad684e53ee39ca9bacd171286528b527586b6a0236a0' 
  AND token = 'jIGzB8rxrXZu7aL+5/1A4mwXs1Y37/PgXQcCo0x5XhI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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