SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '016900164f8485df552d319b734c57484f3ae829363d527f9e545bee612d2878' 
  AND token = 'RYIDNML9cWmDHqJL+V2ObzGcSodWFv69IBQnRuI+hGE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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