SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e6a25e741586da9643d0acbfec9d3f42ff90f8200b04d8af8907101fa0023113' 
  AND token = 'zlhiA/fRAEFGADzHITZ7SRNkkjVfmuNtzUWygBK5oIU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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