SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3766760b0489bbd4d700379f3e4468ac269b0d3fee57f62463a6ff50b5fd3023' 
  AND token = 'bSdiAg6Yyui9ope+NrNWU0zNHzYwSvkBXrdMLVBMZy4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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