SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e5fc23afd8eb6900605f3219ba9a640d73d12430bac8b808edc45b0d2d621b39' 
  AND token = 'PgahtGFFomvKl3Nmc/ywyARs7UuOfw95jZj1h/zdBpo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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