SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '5b688bbfb87188d7d68384fd7d1f31f4130992b1934104e7caf7aea518896f84' 
  AND token = 'fInOs+gXeupFnzFq5Zh9VmaZlzF/1neBgP6HGGqlXC8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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