SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6e66df42201b07d24dde9d7c5b25c7b704e5832f124be16a4ba23a5fde5597ef' 
  AND token = 'vxo68ImqBWvMajMftnITlQEH4ycnXvrhpYEmVGg9dpQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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