SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '24b4ed959e0e71179bcfdca6bf36a2a2859858363102a0dd9033684369697725' 
  AND token = 'MU5mAiSLtvJzSmDStSZ15ptZp3MjJkWqd6azvB7YXTc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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