SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '2c2a6dc2631d2c61774719837e695261a075a28aeed410183521ab92407f997a' 
  AND token = 'DB8nAFZk+Q/i78K8cUzma2lyATR+0OY5P5KsLjynovE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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