SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f706f404e99c60ec478b93732828f5251dc86b0c6487ac6d2efe1f353c25ce0d' 
  AND token = 'LwN3H+8lNXsvVzinB/pBsJl0OCYGowCbnnmhMuxF/0I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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