SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '70263a5a3f7790d90d27e037b526beba6e2a4b6bf032d9c8b099936e4f5d7637' 
  AND token = '2EV6GO6pwzH2S8qnYr5RafzD3s2LpyXrVJ9IdAciE2I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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