SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '68209a9141f5b02751609a8cf2dabd708c6ff4cd535fd1d8c910c8a60446f40a' 
  AND token = 'M1bYjZRdYZZm7umg/cen2sO4BKNJ0dmnDpOWWLuArlU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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