SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a3c5a596a52e4127086739573dca42888bfc258997ed6b68052f0b41a7f721e9' 
  AND token = 'FXePApk9HeF3O8fr3heA5x0DIGXb0YLU6OKEa8b9z9g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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