SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a9a1cd8121066bc70df7fc793e00656c442fbbad7320ab890bf893bc6f14af02' 
  AND token = '1BipeUrTNCpKpDFhWVIuFyZ4u/CUAPALxrwzbS1ufVk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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