SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4ff732b1601b68b6b478cb6a376837c7dab9f41594bcb49505bde46a7172b38' 
  AND token = 'bBq6iRCEvAjZQSU2m4VswIKe3NbYz497B4MhYoFjq0Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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