SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16fa8446f37877a1b21af283ed6dfdad1e2853b371babe07c98246dc7db19a4d' 
  AND token = 'gXC+HNjUf+hwrvZCNDbmaEo9QVr3GLGl1MC8uCm+D1Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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