SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3d21a10514a0f86483e2aef1497318a0a3dc95b4cdb6d1a46a0b6280206559e5' 
  AND token = 'rPQwd+oVhdA563K1bxv7RcoEYt8tSqD1lklfxCP5+iU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00047

JSON explain

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