SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6f1e29708a56aabb53da4f1135d949811573cc9c994fa47ade7f3d36e351fd94' 
  AND token = 'd3QkSE7OetZQDim9T2Bhrb+xN+lXBQm/jW7T6bjyuDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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