SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff4a2e47893aed124068db6ced64224fca6279cc35833993ce2d1e714b1e129b' 
  AND token = 'If7tCCPD15J/rc8vjyqJ3ICMSyXMw1SWVTpGWft+u3M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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