SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3b73300c6f316829bb89d05051847151a820fddda631a55e6414baedeebaa383' 
  AND token = 'k+Pqov3HbJ0UVvU8/eNzG/TkTBulaa6liD6v4BCCjwo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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