SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7ac8793868b70bfc185937a8daf3507fc47f7c6329c4d347dd9abf0574f98f33' 
  AND token = 'WmU8PCuSdPgm7Ek+GDHdkjq78Y+SgHEbKCc5CqTxces=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}