SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b15004dcd4d81e213e10ef1092e47586a431cc336682cfc44f992db8c2bfc99' 
  AND token = 'CYCj3POGabxRccADNSq+JdMeK8PYLVz4llVGVvUKqKo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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