SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5f34b716c206888d7002a1e901842254b0e0b9e9993f14588c6c820d741377c8' 
  AND token = 'MBhIzojPU6uXZHyagbVf8kTdK6yeHSjmkVR+fuFvutw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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