SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b4b62484495aebaa3b93abbc014e85213641cafe1ea9434f6e601988bd1bc0e3' 
  AND token = 'gkVtEuVHIwrp10IelbzkB4orQBH47wz/z5xQGZQtfoQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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