SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9ecae91ecd20df776423eddb85eb1716570421f224fcc799252dbef866673bec' 
  AND token = 'SmSNeENLHIrs+cqLlJtjOdug4GdiW5sNCXY3kWPvOU8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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