SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3968b881ca26e4189207bca44e72bcddf7710266f22c7e2327c1ccc160bb03a' 
  AND token = 'JU/T+os1PbbBnF7c434K9k3Wo2hONYkTctl2vyzZ68g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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