SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '853e07edb2500379136d6cdf3a6790281eb658a597254810d48092b74e0f7c14' 
  AND token = 'DAFmYIfhdJjvdpxUGallp4RCzi1UngExpO4cQivr0VA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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