SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a67f12abbda4a8dcda2f6cedbd074c9673e197a8c340bbd35be5426de50e3539' 
  AND token = 'vBOoxACf5ypx5nqoGs8iRilOfYY18zyzYLL5l0tSQwY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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