SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cafc394cab18b8150f080b050c2925a881db04eab4e073c15793df443bbc6f41' 
  AND token = 'JyL2X28AA92MsZDa3SXSZnLaN1djBo4kZMPfP1PZtMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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